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Author | Mary Joy, R.; Pobedinskas, P.; Baule, N.; Bai, S.; Jannis, D.; Gauquelin, N.; Pinault-Thaury, M.-A.; Jomard, F.; Sankaran, K.J.; Rouzbahani, R.; Lloret, F.; Desta, D.; D’Haen, J.; Verbeeck, J.; Becker, M.F.; Haenen, K. | ||||
Title | The effect of microstructure and film composition on the mechanical properties of linear antenna CVD diamond thin films | Type | A1 Journal article | ||
Year | 2024 | Publication | Acta materialia | Abbreviated Journal | Acta Materialia |
Volume | 264 | Issue | Pages | 119548 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | This study reports the impact of film microstructure and composition on the Young’s modulus and residual stress in nanocrystalline diamond (NCD) thin films ( thick) grown on silicon substrates using a linear antenna microwave plasma-enhanced chemical vapor deposition (CVD) system. Combining laser acoustic wave spectroscopy to determine the elastic properties with simple wafer curvature measurements, a straightforward method to determine the intrinsic stress in NCD films is presented. Two deposition parameters are varied: (1) the substrate temperature from 400 °C to 900 °C, and (2) the [P]/[C] ratio from 0 ppm to 8090 ppm in the H2/CH4/CO2/PH3 diamond CVD plasma. The introduction of PH3 induces a transition in the morphology of the diamond film, shifting from NCD with larger grains to ultra-NCD with a smaller grain size, concurrently resulting in a decrease in Young’s modulus. Results show that the highest Young’s modulus of (113050) GPa for the undoped NCD deposited at 800 °C is comparable to single crystal diamond, indicating that NCD with excellent mechanical properties is achievable with our process for thin diamond films. Based on the film stress results, we propose the origins of tensile intrinsic stress in the diamond films. In NCD, the tensile intrinsic stress is attributed to larger grain size, while in ultra-NCD films the tensile intrinsic stress is due to grain boundaries and impurities. | ||||
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Language | Wos | 001126632800001 | Publication Date | 2023-11-23 | |
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ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 9.4 | Times cited | Open Access | Not_Open_Access | |
Notes | This work was financially supported by the Special Research Fund (BOF) via Methusalem NANO network, the Research Foundation – Flanders (FWO) via Project G0D4920N, and the CORNET project nr 263-EN “ULTRAHARD: Ultrahard optical diamond coatings” (2020–2021). | Approved | Most recent IF: 9.4; 2024 IF: 5.301 | ||
Call Number | EMAT @ emat @c:irua:202169 | Serial | 8989 | ||
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Author | Coulombier, M.; Baral, P.; Orekhov, A.; Dohmen, R.; Raskin, J.P.; Pardoen, T.; Cordier, P.; Idrissi, H. | ||||
Title | On-chip very low strain rate rheology of amorphous olivine films | Type | A1 Journal article | ||
Year | 2024 | Publication | Acta materialia | Abbreviated Journal | |
Volume | 266 | Issue | Pages | 119693-12 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Recent observations made by the authors revealed the activation of stress induced amorphization and sliding at grain boundary in olivine [1], a mechanism which is expected to play a pivotal role in the viscosity drop at the lithosphere-asthenosphere boundary and the brittle -ductile transition in the lithospheric mantle. However, there is a lack of information in the literature regarding the intrinsic mechanical properties and the elementary deformation mechanisms of this material, especially at time scales relevant for geodynamics. In the present work, amorphous olivine films were obtained by pulsed laser deposition (PLD). The mechanical response including the rate dependent behavior are investigated using a tension -on -chip (TOC) method developed at UCLouvain allowing to perform creep/relaxation tests on thin films at extremely low strain rates. In the present work, strain rate down to 10-12 s- 1 was reached which is unique. High strain rate sensitivity of 0.054 is observed together with the activation of relaxation at the very early stage of deformation. Furthermore, digital image correlation (DIC), used for the first time on films deformed by TOC, reveals local strain heterogeneities. The relationship between such heterogeneities, the high strain rate sensitivity and the effect of the electron beam in the scanning electron microscope is discussed and compared to the literature. | ||||
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Language | Wos | 001170513400001 | Publication Date | 2024-01-17 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 9.4 | Times cited | Open Access | ||
Notes | Approved | Most recent IF: 9.4; 2024 IF: 5.301 | |||
Call Number | UA @ admin @ c:irua:204864 | Serial | 9163 | ||
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Author | Baral, P.; Kashiwar, A.; Coulombier, M.; Delannay, L.; Hoummada, K.; Raskin, J.P.; Idrissi, H.; Pardoen, T. | ||||
Title | Grain boundary-mediated plasticity in aluminum films unraveled by a statistical approach combining nano-DIC and ACOM-TEM | Type | A1 Journal article | ||
Year | 2024 | Publication | Acta materialia | Abbreviated Journal | |
Volume | 276 | Issue | Pages | 120081-14 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Nanomechanical on-chip testing is combined with nanoscale in situ digital image correlation and automated crystal orientation mapping in TEM to deliver novel statistically representative quantitative data about the deformation mechanisms in nanocrystalline aluminum films. The films are very ductile, with a rare stable multiple necking process with local strains reaching up to 0.45 and macroscopic elongation up to 0.17. The strain fields with resolution below 100 nm are related to the underlying microstructure and crystallographic orientation maps. This reveals nanoscopic shear bands forming preferentially along GB with high misorientations, tilted at +/− 45° with respect to loading direction. The analysis of these data prove that the strong strain delocalization process is promoted by GB migration and grain rotation, leading to large strain rate sensitivity. The distribution of misorientation angles between grains evolve during deformation. The GBs with misorientation between 20° and 40°, which are the GBs with highest energy, involve the largest strains. | ||||
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Language | Wos | https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=brocade2&SrcAuth=WosAPI&KeyUT=WOS:001258 | Publication Date | 2024-06-04 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record | |
Impact Factor | 9.4 | Times cited | Open Access | ||
Notes | Approved | Most recent IF: 9.4; 2024 IF: 5.301 | |||
Call Number | UA @ admin @ c:irua:206419 | Serial | 9294 | ||
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Author | Choisez, L.; Ding, L.; Marteleur, M.; Kashiwar, A.; Idrissi, H.; Jacques, P.J. | ||||
Title | Shear banding-activated dynamic recrystallization and phase transformation during quasi-static loading of β-metastable Ti – 12 wt % Mo alloy | Type | A1 Journal article | ||
Year | 2022 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 235 | Issue | Pages | 118088-13 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Dynamic recrystallization (DRX) within adiabatic shear bands forming during the fracture of TRIP-TWIP β−metastable Ti-12Mo (wt %) alloy was recently reported. The formation of 1-3 µm thick-adiabatic shear bands, and of dynamic recrystallization, was quite surprising as their occurrence generally requires high temperature and/or high strain rate loading while these samples were loaded in quasi-static conditions at room temperature. To better understand the fracture mechanism and associated microstructural evolution, thin foils representative of different stages of the fracture process were machined from the fracture surface by Focused Ion Beam (FIB) and analyzed by Transmission Electron Microscopy (TEM) and Automated Crystal Orientation mapping (ACOM-TEM). Complex microstructure transformations involving severe plastic deformed nano-structuration, crystalline rotation and local precipitation of the omega phase were identified. The spatial and temporal evolution of the microstructure during the propagation of the crack was explained through dynamic recovery and continuous dynamic recrystallization, and linked to the modelled distribution of temperature and strain level where TEM samples were extracted. | ||||
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Language | Wos | 000814729300005 | Publication Date | 2022-06-05 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 9.4 | Times cited | Open Access | OpenAccess | |
Notes | Approved | Most recent IF: 9.4 | |||
Call Number | UA @ admin @ c:irua:188505 | Serial | 7096 | ||
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Author | Arseenko, M.; Hannard, F.; Ding, L.; Zhao, L.; Maire, E.; Villanova, J.; Idrissi, H.; Simar, A. | ||||
Title | A new healing strategy for metals : programmed damage and repair | Type | A1 Journal article | ||
Year | 2022 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 238 | Issue | Pages | 118241-10 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Self-healing strategies aim at avoiding part repair or even replacement, which is time consuming, expen-sive and generates waste. However, strategies for metallic systems are still under-developed and solid-state solutions for room temperature service are limited to nano-scale damage repair. Here we propose a new healing strategy of micron-sized damage requiring only short and low temperature heating. This new strategy is based on damage localization particles, which can be healed by fast diffusing atoms of the matrix activated during heat treatment. The healing concept was successfully validated with a com-mercial aluminum alloy and manufactured by Friction Stir Processing (FSP). Damage was demonstrated to initiate on particles that were added to the matrix during material processing. In situ 2D and 3D nano -imaging confirmed healing of the damaged material and showed that heating this material for 10 min at 400 degrees C is sufficient to heal incipient damage with complete filling of 70% of all damage (and up to 90% when their initial size is below 0.2 mu m). Furthermore, strength is retained and the work of fracture of the alloy is improved by about 40% after healing. The proposed Programmed Damage and Repair healing strategy could be extended to other metal based systems presenting precipitation. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Language | Wos | 000843502700006 | Publication Date | 2022-08-03 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 9.4 | Times cited | Open Access | Not_Open_Access | |
Notes | Approved | Most recent IF: 9.4 | |||
Call Number | UA @ admin @ c:irua:190561 | Serial | 7121 | ||
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Author | Idrissi, H.; Béché, A.; Gauquelin, N.; Ul-Haq, I.; Bollinger, C.; Demouchy, S.; Verbeeck, J.; Pardoen, T.; Schryvers, D.; Cordier, P. | ||||
Title | On the formation mechanisms of intragranular shear bands in olivine by stress-induced amorphization | Type | A1 Journal article | ||
Year | 2022 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 239 | Issue | Pages | 118247-118249 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Intragranular amorphization shear lamellae are found in deformed olivine aggregates. The detailed trans-mission electron microscopy analysis of intragranular lamella arrested in the core of a grain provides novel information on the amorphization mechanism. The deformation field is complex and heteroge-neous, corresponding to a shear crack type instability involving mode I, II and III loading components. The formation and propagation of the amorphous lamella is accompanied by the formation of crystal defects ahead of the tip. These defects are geometrically necessary [001] dislocations, characteristics of high-stress deformation in olivine, and rotational nanodomains which are tentatively interpreted as disclinations. We show that these defects play an important role in dictating the path followed by the amorphous lamella. Stress-induced amorphization in olivine would thus result from a direct crystal-to -amorphous transformation associated with a shear instability and not from a mechanical destabilization due to the accumulation of high number of defects from an intense preliminary deformation. The pref-erential alignment of some lamellae along (010) is a proof of the lower ultimate mechanical strength of these planes.(c) 2022 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ ) | ||||
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Language | Wos | 000861076600004 | Publication Date | 2022-08-05 | |
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ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 9.4 | Times cited | 5 | Open Access | OpenAccess |
Notes | The QuanTEM microscope was partially funded by the Flemish government. The K2 camera was funded by FWO Hercules fund G0H4316N 'Direct electron detector for soft matter TEM'. A. Beche acknowledges funding from FWO project G093417N ('Compressed sensing enabling low dose imaging in transmission electron microscopy'). H. Idrissi is mandated by the Belgian National Fund for Scientific Research (FSR-FNRS). This work was supported by the FNRS under Grant PDR – T011322F and by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreement No 787,198 Time Man. J-L Rouviere is acknowledged for his support with the GPA softawre. | Approved | Most recent IF: 9.4 | ||
Call Number | UA @ admin @ c:irua:191432 | Serial | 7186 | ||
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Author | Ghidelli, M.; Orekhov, A.; Bassi, A.L.; Terraneo, G.; Djemia, P.; Abadias, G.; Nord, M.; Béché, A.; Gauquelin, N.; Verbeeck, J.; Raskin, J.-p.; Schryvers, D.; Pardoen, T.; Idrissi, H. | ||||
Title | Novel class of nanostructured metallic glass films with superior and tunable mechanical properties | Type | A1 Journal article | ||
Year | 2021 | Publication | Acta Materialia | Abbreviated Journal | Acta Mater |
Volume | Issue | Pages | 116955 | ||
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | A novel class of nanostructured Zr50Cu50 (%at.) metallic glass films with superior and tunable mechanical properties is produced by pulsed laser deposition. The process can be controlled to synthetize a wide range of film microstructures including dense fully amorphous, amorphous embedded with nanocrystals and amorphous nano-granular. A unique dense self-assembled nano-laminated atomic arrangement characterized by alternating Cu-rich and Zr/O-rich nanolayers with different local chemical enrichment and amorphous or amorphous-crystalline composite nanostructure has been discovered, while significant in-plane clustering is reported for films synthetized at high deposition pressures. This unique nanoarchitecture is at the basis of superior mechanical properties including large hardness and elastic modulus up to 10 and 140 GPa, respectively and outstanding total elongation to failure (>9%), leading to excellent strength/ductility balance, which can be tuned by playing with the film architecture. These results pave the way to the synthesis of novel class of engineered nanostructured metallic glass films with high structural performances attractive for a number of applications in microelectronics and coating industry. |
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Language | Wos | 000670077800004 | Publication Date | 2021-05-12 | |
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Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 27 | Open Access | OpenAccess |
Notes | H.I. is mandated by the Belgian National Fund for Scientific Research (FSR-FNRS). This work was supported by the Fonds de la Recherche Scientifique – FNRS under Grant T.0178.19 and Grant CDR– J011320F. We acknowledge funding for the direct electron detector used in the 4D stem studies from the Hercules fund 'Direct electron detector for soft matter TEM' from the Flemish Government J.V acknowledges funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 823717 – ESTEEM3. A.O. has received partial funding from the GOA project “Solarpaint” of the University of Antwerp. A.B. and J.V. acknowledge funding through FWO project G093417N ('Compressed sensing enabling low dose imaging in transmission electron microscopy') from the Flanders Research Fund. M.G. and A.L.B acknowledge Chantelle Ekanem for support in PLD depositions. | Approved | Most recent IF: 5.301 | ||
Call Number | EMAT @ emat @c:irua:178142 | Serial | 6761 | ||
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Author | Baral, P.; Orekhov, A.; Dohmen, R.; Coulombier, M.; Raskin, J.P.; Cordier, P.; Idrissi, H.; Pardoen, T. | ||||
Title | Rheology of amorphous olivine thin films characterized by nanoindentation | Type | A1 Journal article | ||
Year | 2021 | Publication | Acta Materialia | Abbreviated Journal | Acta Mater |
Volume | 219 | Issue | Pages | 117257 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The rheological properties of amorphous olivine thin films deposited by pulsed laser deposition have been studied based on ambient temperature nanoindentation under constant strain-rate as well as re-laxation conditions. The amorphous olivine films exhibit a viscoelastic-viscoplastic behavior with a significant rate dependency. The strain-rate sensitivity m is equal to similar to 0 . 05 which is very high for silicates, indicating a complex out-of-equilibrium structure. The minimum apparent activation volume determined from nanoindentation experiments corresponds to Mg and Fe atomic metallic sites in the (Mg,Fe)(2)SiO4 crystalline lattice. The ambient temperature creep behavior of the amorphous olivine films differs very much from the one of single crystal olivine. This behavior directly connects to the recent demonstration of the activation of grain boundary sliding in polycrystalline olivine following grain boundary amorphization under high-stress. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. | ||||
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Language | Wos | 000706867800004 | Publication Date | 2021-08-19 | |
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Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | Open Access | OpenAccess | |
Notes | Approved | Most recent IF: 5.301 | |||
Call Number | UA @ admin @ c:irua:182592 | Serial | 6882 | ||
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Author | Yang, M.; Orekhov, A.; Hu, Z.-Y.; Feng, M.; Jin, S.; Sha, G.; Li, K.; Samaee, V.; Song, M.; Du, Y.; Van Tendeloo, G.; Schryvers, D. | ||||
Title | Shearing and rotation of β'' and β' precipitates in an Al-Mg-Si alloy under tensile deformation : in-situ and ex-situ studies | Type | A1 Journal article | ||
Year | 2021 | Publication | Acta Materialia | Abbreviated Journal | Acta Mater |
Volume | 220 | Issue | Pages | 117310 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The interaction between dislocations and nano-precipitates during deformation directly influences hardening response of precipitation-strengthening metals such as Al-Mg-Si alloys. However, how coherent and semi-coherent nano-precipitates accommodate external deformation applied to an Al alloy remains to be elucidated. In-situ tensile experiments in a transmission electron microscope (TEM) were conducted to study the dynamic process of dislocations cutting through coherent needle-like beta '' precipitates with diameters of 3 similar to 8 nm. Comprehensive investigations using in-situ, ex-situ TEM and atom probe tomography uncovered that beta '' precipitates were firstly sheared into small fragments, and then the rotation of the fragments, via sliding along precipitate/matrix interfaces, destroyed their initially coherent interface with the Al matrix. In contrast, semi-coherent beta' precipitates with sizes similar to beta '' were more difficult to be fragmented and accumulation of dislocations at the interface increased interface misfit between beta' and the Al matrix. Consequently, beta' precipitates could basically maintain their needle-like shape after the tensile deformation. This research gains new insights into the interaction between nano-precipitates and dislocations. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Language | Wos | 000705535300005 | Publication Date | 2021-09-12 | |
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Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | Open Access | OpenAccess | |
Notes | Approved | Most recent IF: 5.301 | |||
Call Number | UA @ admin @ c:irua:182528 | Serial | 6884 | ||
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Author | Cautaerts, N.; Delville, R.; Stergar, E.; Pakarinen, J.; Verwerft, M.; Yang, Y.; Hofer, C.; Schnitzer, R.; Lamm, S.; Felfer, P.; Schryvers, D. | ||||
Title | The role of Ti and TiC nanoprecipitates in radiation resistant austenitic steel: A nanoscale study | Type | A1 Journal article | ||
Year | 2020 | Publication | Acta Materialia | Abbreviated Journal | Acta Mater |
Volume | 197 | Issue | Pages | 184-197 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | This work encompasses an in-depth transmission electron microscopy and atom probe tomography study of Ti-stabilized austenitic steel irradiated with Fe-ions. The focus is on radiation induced segregation and precipitation, and in particular on how Ti and TiC affect these processes. A 15-15Ti steel (grade: DIN 1.4970) in two thermo-mechanical states (cold-worked and aged) was irradiated at different temperatures up to a dose of 40 dpa. At low irradiation temperatures, the cold-worked and aged materials evolved to a similar microstructure dominated by small Si and Ni clusters, corresponding to segregation to small point defect clusters. TiC precipitates, initially present in the aged material, were found to be unstable under these irradiation conditions. Elevated irradiation temperatures resulted in the nucleation of nanometer sized Cr enriched TiC precipitates surrounded by Si and Ni enriched shells. In addition, nanometer sized Ti- and Mn-enriched G-phase (M6Ni16Si7) precipitates formed, often attached to TiC precipitates. Post irradiation, larger number densities of TiC were observed in the cold-worked material compared to the aged material. This was correlated with a lower volume fraction of G-phase. The findings suggest that at elevated irradiation temperatures, the precipitate-matrix interface is an important point defect sink and contributes to the improved radiation resistance of this material. The study is a first of its kind on stabilized steel and demonstrates the significance of the small Ti addition to the evolution of the microstructure under irradiation. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Language | Wos | 000564767000001 | Publication Date | 2020-07-10 | |
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ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 9.4 | Times cited | Open Access | Not_Open_Access | |
Notes | ; This work was supported by ENGIE [contract number 2015-AC-007 e BSUEZ6900]; the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07051D14517 as part of a Nuclear Science User Facilities experiment; and by the MYRRHA program at SCK-CEN, Belgium. Funding of the Austrian BMK (846933) in the framework of the program “Production of the future” and the “BMK Professorship for Industry” is gratefully acknowledged. We want to thank the staffat MIBL for assisting with the ion irradiations as well as the staffat CAES for assisting with FIB work and conducting APT measurements. ; | Approved | Most recent IF: 9.4; 2020 IF: 5.301 | ||
Call Number | UA @ admin @ c:irua:171956 | Serial | 6626 | ||
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Author | Cautaerts, N.; Delville, R.; Stergar, E.; Schryvers, D.; Verwerft, M. | ||||
Title | Characterization of (Ti,Mo,Cr)C nanoprecipitates in an austenitic stainless steel on the atomic scale | Type | A1 Journal article | ||
Year | 2019 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 164 | Issue | Pages | 90-98 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Nanometer sized (Ti,Mo,Cr)C (MX-type) precipitates that grew in a 24% cold worked Ti-stabilized austenitic stainless steel (grade DIN 1.4970, member of the 15-15Ti austenitic stainless steels) after heat treatment were fully characterized with transmission electron microscopy (TEM), probe corrected high angle annular dark field scanning transmission electron microscopy (HR-HAADF STEM), and atom probe tomography (APT). The precipitates shared the cube-on-cube orientation with the matrix and were facetted on {111} planes, yielding octahedral and elongated octahedral shapes. The misfit dislocations were believed to have Burgers vectors a/6<112> which was verified by geometrical phase analysis (GPA) strain mapping of a matrix-precipitate interface. The dislocations were spaced five to seven atomic planes apart, on average slightly wider than expected for the lattice parameters of steel and TiC. Quantitative atom probe tomography analysis of the precipitates showed that precipitates were significantly enriched in Mo, Cr and V, and that they were hypostoichiometric with respect to C. These findings were consistent with a reduced lattice parameter. The precipitates were found primarily on Shockley partial dislocations originating from the original perfect dislocation network. These novel findings could contribute to the understanding of how TiC nanoprecipitates interact with point defects and matrix dislocations. This is essential for the application of these Ti-stabilized steels in high temperature environments or fast spectrum nuclear fission reactors. |
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Language | Wos | 000456902800008 | Publication Date | 2018-10-11 | |
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ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 2 | Open Access | Not_Open_Access: Available from 12.10.2020 |
Notes | This work was supported by ENGIE [contract number 2015-AC- 007 e BSUEZ6900]; the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07- 051D14517 as part of a Nuclear Science User Facilities experiment; and by the MYRRHA program in development at SCKCEN, Belgium. Special thanks to Dr. H. Mezerji and Dr. T. Altantzis for the work on the FEI Titan microscope.We also want to thank Ms. J. Burns for the help on the FIB and Dr. Y. Wu at CAES for conducting the APT measurements. | Approved | Most recent IF: 5.301 | ||
Call Number | EMAT @ emat @c:irua:154873UA @ admin @ c:irua:154873 | Serial | 5060 | ||
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Author | Zhang, Z.; Rosalie, J.M.; Medhekar, N.V.; Bourgeois, L. | ||||
Title | Resolving the FCC/HCP interfaces of the \gamma'(Ag2Al) precipitate phase in aluminium | Type | A1 Journal article | ||
Year | 2019 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 174 | Issue | 174 | Pages | 116-130 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The gamma'(Ag2Al) phase in the Al-Ag alloy system has served as a textbook example for understanding phase transformations, precipitating hexagonal close-packed (HCP) crystals in the face-centred cubic (FCC) aluminium matrix. The gamma' precipitates display fully coherent interfaces at their broad facets and semicoherent interfaces at their edges. Shockley partial dislocations are expected to decorate the semicoherent interface due to the FCC-HCP structural transformation. Determining the exact locations and core structures of interfacial dislocations, however, remains challenging. In this study, we used aberration-corrected scanning transmission electron microscopy and atomistic simulations to re-visit this classical system. We characterised and explained the Ag segregation at coherent interfaces in the early stage of precipitation. For semicoherent interfaces, interfacial dislocations and reconstructions were revealed by bridging advanced microstructure characterisation and atomistic simulations. In particular, we discovered a new FCC/HCP interfacial structure that displays a unique combination of Shockley partial, Lomer-Cottrell and Hirth dislocations that evolve from the known interfacial structure purely composed by Shockley partial dislocations. Our findings show that the FCC-HCP transformation is more complex than hitherto considered, due to the interplay between structure and composition confined at interfaces. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Language | Wos | 000474501300011 | Publication Date | 2019-05-18 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 3 | Open Access | |
Notes | ; The authors acknowledge funding from the Australian Research Council (LE0454166, LE110100223), the Victorian State Government and Monash University for instrumentation, and use of the facilities within the Monash Centre for Electron Microscopy. LB and NM acknowledge the financial support of the Australian Research Council (DP150100558). The authors also gratefully acknowledge the computational support from Monash Advanced Research Computing Hybrid, the National Computational Infrastructure and Pawsey Supercomputing Centre. ZZ is thankful to Monash University for a Monash Graduate Scholarship, a Monash International Postgraduate Research Scholarship and a Monash Centre for Electron Microscopy Postgraduate Scholarship. ZZ is indebted to Matthew Weyland for his training in aberration-corrected electron microscopy, Scott Findlay for his help on image simulations, Xiang Gao for alloy casting and Ian Polmear for discussions. ; | Approved | Most recent IF: 5.301 | ||
Call Number | UA @ admin @ c:irua:161192 | Serial | 5395 | ||
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Author | Weng, Y.; Ding, L.; Zhang, Z.; Jia, Z.; Wen, B.; Liu, Y.; Muraishi, S.; Li, Y.; Liu, Q. | ||||
Title | Effect of Ag addition on the precipitation evolution and interfacial segregation for Al-Mg-Si alloy | Type | A1 Journal article | ||
Year | 2019 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 180 | Issue | 180 | Pages | 301-316 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The effect of Ag addition on the precipitation evolution and interfacial segregation for Al-Mg-Si alloys was systematically investigated by atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), atom probe tomography (APT) and density functional theory (DFT) calculation. At the early aging stage, Ag atoms could enter clusters and refine the distribution of these clusters. Then, Ag atoms preferentially segregate at the GP zone/alpha-Al and beta ''/alpha-Al interfaces at the peak aging stage by the replacement of Al atoms in FCC matrix. With prolonging aging time, Ag atoms generally incorporate into the interior of beta '' precipitate, facilitating the formation of QP lattice (a hexagonal network of Si atomic columns) and the local symmetry substructures, Ag sub-unit (1) and Ag sub-unit (2). At the over-aged stage, the Ag sub-unit (1) and Ag sub-unit (2) could transform to the beta'(Ag) (i.e. beta'(Ag1) and beta'(Ag2).) and Q'(Ag) unit cells, respectively. All the precipitates at the over-aging stage have a composite and disordered structure due to the coexistence of different unit cells (beta'(Ag1), beta'(Ag2), Q'(Ag) and beta') and the non-periodic arrangement of Ag atoms within the precipitate. In the equilibrium stage, the incorporated Ag atoms in the precipitates release into the alpha-Al matrix as solute atoms or form Ag particles. In general, Ag atoms undergo a process of “segregate at the precipitate/matrix interface -> incorporate into the interior of precipitate -> release into the alpha-Al matrix” during the precipitation for Al-Mg-Si-Ag alloys. Besides, Ag segregation is found at the interfaces of almost all metastable phases (including GP zone, beta '', beta'/beta'(Ag) phase) in Al-Mg-Si-Ag alloys. The Ag segregation at the beta'/alpha-Al interface could increase the length/diameter ratio of beta' phase and thus promote the additional strengthening potential of these alloys. These findings provide a new route for precipitation hardening by promoting the nucleation and morphology evolution of precipitates. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000495519100028 | Publication Date | 2019-09-12 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | Open Access | ||
Notes | Approved | Most recent IF: 5.301 | |||
Call Number | UA @ admin @ c:irua:164641 | Serial | 6295 | ||
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Author | van der Rest, A.; Idrissi, H.; Henry, F.; Favache, A.; Schryvers, D.; Proost, J.; Raskin, J.-P.; Van Overmeere, Q.; Pardoen, T. | ||||
Title | Mechanical behavior of ultrathin sputter deposited porous amorphous Al2O3 films | Type | A1 Journal article | ||
Year | 2017 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 125 | Issue | 125 | Pages | 27-37 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The determination of the mechanical properties of porous amorphous Al2O3 thin films is essential to address reliability issues in wear-resistant, optical and electronic coating applications. Testing the mechanical properties of Al2O3 films thinner than 200 nm is challenging, and the link between the mechanical behavior and the microstructure of such films is largely unknown. Herein, we report on the elastic and viscoplastic mechanical properties of amorphous Al2O3 thin films synthesized by reactive magnetron sputtering using a combination of internal stress, nanoindentation, and on-chip uniaxial tensile testing, together with mechanical homogenization models to separate the effect of porosity from intrinsic variations of the response of the sound material. The porosity is made of voids with 2e30 nm diameter. The Young's modulus and hardness of the films decrease by a factor of two when the deposition pressure increases from 1.2 to 8 mTorr. The contribution of porosity was found to be small, and a change in the atomic structure of the amorphous Al2O3 matrix is hypothesized to be the main contributing factor. The activation volume associated to the viscoplastic deformation mechanism is around 100 Å3. Differences in the atomic structure of the films could not be revealed by electron diffraction, pointing to a minute effect of atomic arrangement on the elastic properties. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000394201500003 | Publication Date | 2016-12-02 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 5 | Open Access | OpenAccess |
Notes | This work has been funded by the Belgian Science Policy through the IAP 7/21 project. The support of the ‘Fonds Belge pour la Recherche dans l’Industrie et l’Agriculture (FRIA)’ for A.v.d.R. is also gratefully acknowledged, as well as the support of FNRS through the grant PDR T.0122.13 “Mecano”. | Approved | Most recent IF: 5.301 | ||
Call Number | EMAT @ emat @ c:irua:138990 | Serial | 4330 | ||
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Author | Ghidelli, M.; Idrissi, H.; Gravier, S.; Blandin, J.-J.; Raskin, J.-P.; Schryvers, D.; Pardoen, T. | ||||
Title | Homogeneous flow and size dependent mechanical behavior in highly ductile Zr 65 Ni 35 metallic glass films | Type | A1 Journal article | ||
Year | 2017 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 131 | Issue | 131 | Pages | 246-259 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Motivated by recent studies demonstrating a high strength – high ductility potential of nano-scale metallic glass samples, the mechanical response of freestanding Zr65Ni35 film with sub-micron thickness has been investigated by combining advanced on-chip tensile testing and electron microscopy. Large deformation up to 15% is found for specimen thicknesses below 500 nm with variations depending on specimen size and frame compliance. The deformation is homogenous until fracture, with no evidence of shear banding. The yield stress is doubled when decreasing the specimen cross-section, reaching ~3 GPa for small cross-sections. The fracture strain variation is related to both the stability of the test device and to the specimen size. The study concludes on clear disconnect between the mechanisms controlling the onset of plasticity and the fracture process. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000402343400023 | Publication Date | 2017-03-31 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 42 | Open Access | OpenAccess |
Notes | This work has been funded by the Belgian Science Policy through the IAP 7/21 project. We acknowledge IDS-FunMat for the PhD financial support.We thank the Renatech network and the PTA (Plateforme Technologique Amont) in Grenoble (France) for TFMG deposition facilities. The WINFAB infrastructure at the UCL and the help of R. Vayrette and M. Coulombier for the on-chip tests. H. Idrissi is currently mandated by the Belgian National Fund for Scientific Research (FSR-FNRS). | Approved | Most recent IF: 5.301 | ||
Call Number | EMAT @ emat @ c:irua:142642 | Serial | 4562 | ||
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Author | Hoang, D.-Q.; Korneychuk, S.; Sankaran, K.J.; Pobedinskas, P.; Drijkoningen, S.; Turner, S.; Van Bael, M.K.; Verbeeck, J.; Nicley, S.S.; Haenen, K. | ||||
Title | Direct nucleation of hexagonal boron nitride on diamond : crystalline properties of hBN nanowalls | Type | A1 Journal article | ||
Year | 2017 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 127 | Issue | Pages | 17-24 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Hexagonal boron nitride (hBN) nanowalls were deposited by unbalanced radio frequency sputtering on (100)-oriented silicon, nanocrystalline diamond films, and amorphous silicon nitride (Si3N4) membranes. The hBN nanowall structures were found to grow vertically with respect to the surface of all of the substrates. To provide further insight into the nucleation phase and possible lattice distortion of the deposited films, the structural properties of the different interfaces were characterized by transmission electron microscopy. For Si and Si3N4 substrates, turbostratic and amorphous BN phases form a clear transition zone between the substrate and the actual hBN phase of the bulk nanowalls. However, surprisingly, the presence of these phases was suppressed at the interface with a nanocrystalline diamond film, leading to a direct coupling of hBN with the diamond surface, independent of the vertical orientation of the diamond grain. To explain these observations, a growth mechanism is proposed in which the hydrogen terminated surface of the nanocrystalline diamond film leads to a rapid formation of the hBN phase during the initial stages of growth, contrary to the case of Si and Si3N4 substrates. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | Publication Date | |||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; ; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | Open Access | OpenAccess | |
Notes | Approved | Most recent IF: 5.301 | |||
Call Number | UA @ lucian @ c:irua:142398 | Serial | 4645 | ||
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Author | Amin-Ahmadi, B.; Connétable, D.; Fivel, M.; Tanguy, D.; Delmelle, R.; Turner, S.; Malet, L.; Godet, S.; Pardoen, T.; Proost, J.; Schryvers, D.; Idrissi, H. | ||||
Title | Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films | Type | A1 Journal article | ||
Year | 2016 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 111 | Issue | 111 | Pages | 253-261 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000375812100027 | Publication Date | 2016-04-06 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 14 | Open Access | |
Notes | This work was carried out in the framework of the IAP program of the Belgian State Federal Office for Scientific, Technical and Cultural Affairs, under Contract No. P7/21. The support of the FWO research project G012012N “Understanding nanocrystalline mechanical behaviour from structural investigations” for B. Amin-Ahmadi is also gratefully acknowledged. This work was granted access to the HPC resources of CALMIP (CICT Toulouse, France) under the allocations 2014-p0912 and 2014-p0749. | Approved | Most recent IF: 5.301 | ||
Call Number | c:irua:132678 | Serial | 4054 | ||
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Author | Zhang, F.; Batuk, M.; Hadermann, J.; Manfredi, G.; Mariën, A.; Vanmeensel, K.; Inokoshi, M.; Van Meerbeek, B.; Naert, I.; Vleugels, J. | ||||
Title | Effect of cation dopant radius on the hydrothermal stability of tetragonal zirconia: Grain boundary segregation and oxygen vacancy annihilation | Type | A1 Journal article | ||
Year | 2016 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 106 | Issue | 106 | Pages | 48-58 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The hydrothermal aging stability of 3Y-TZP-xM2O3 (M = La, Nd, Sc) was investigated as a function of 0.02–5 mol% M2O3 dopant content and correlated to the overall phase content, t-ZrO2 lattice parameters, grain size distribution, grain boundary chemistry and ionic conductivity. The increased aging stability with increasing Sc2O3 content and the optimum content of 0.4–0.6 mol% Nd2O3 or 0.2–0.4 mol% La2O3, resulting in the highest aging resistance, could be directly related to the constituent phases and the lattice parameters of the remaining tetragonal zirconia. At low M2O3 dopant contents ≤0.4 mol%, the different aging behavior of tetragonal zirconia was attributed to the defect structure of the zirconia grain boundary which was influenced by the dopant cation radius. It was observed that the grain boundary ionic resistivity and the aging resistance followed the same trend: La3+ > Nd3+ > Al3+ > Sc3+, proving that hydrothermal aging is driven by the diffusion of water-derived mobile species through the oxygen vacancies. Accordingly, we elucidated the underlying mechanism by which a larger trivalent cation segregating at the zirconia grain boundary resulted in a higher aging resistance. |
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000371650300006 | Publication Date | 2016-01-08 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 37 | Open Access | |
Notes | The authors acknowledge the Research Fund of KU Leuven under project 0T/10/052 and the Fund for Scientific Research Flanders (FWO-Vlaanderen) under grant G.0431.10N. F. Zhang thanks the Research Fund of KU Leuven for her post-doctoral fellowship (PDM/15/153). | Approved | Most recent IF: 5.301 | ||
Call Number | c:irua:132435 | Serial | 4076 | ||
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Author | Lemoine, G.; Delannay, L.; Idrissi, H.; Colla, M.-S.; Pardoen, T. | ||||
Title | Dislocation and back stress dominated viscoplasticity in freestanding sub-micron Pd films | Type | A1 Journal article | ||
Year | 2016 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 111 | Issue | 111 | Pages | 10-21 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | A dislocation-based crystal plasticity model is developed in order to study the mechanical and creep/ relaxation behaviour of polycrystalline metallic thin films. The model accounts for the confinement of plasticity due to grain boundaries and for the anisotropy of individual grains, as well as for the significant viscoplastic effects associated to dislocation dominated thermally activated mechanisms. Numerical predictions are assessed based on experimental tensile test followed by relaxation on freestanding Pd films, based on an on-chip test technique. The dislocation-based mechanism assumption captures all the experimental trends, including the stress strain response, the relaxation behaviour and the dislocation density evolution, confirming the dominance of a dislocation driven deformation mechanism for the present Pd films with high defects density. The model has also been used to address some original experimental evidences involving back stresses, Bauschinger effect, backward creep and strain recovery. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000375812100002 | Publication Date | 2016-03-26 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 6 | Open Access | |
Notes | Approved | Most recent IF: 5.301 | |||
Call Number | UA @ lucian @ c:irua:133636 | Serial | 4162 | ||
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Author | Wang, X.; Kustov, S.; Li, K.; Schryvers, D.; Verlinden, B.; Van Humbeeck, J. | ||||
Title | Effect of nanoprecipitates on the transformation behavior and functional properties of a Ti50.8 at.% Ni alloy with micron-sized grains | Type | A1 Journal article | ||
Year | 2015 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 82 | Issue | 82 | Pages | 224-233 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | In order to take advantage of both grain refinement and precipitation hardening effects, nanoscaled Ni4Ti3 precipitates are introduced in a Ti50.8 at.% Ni alloy with micron-sized grains (average grain size of 1.7 μm). Calorimetry, electrical resistance studies and thermomechanical tests were employed to study the transformation behavior and functional properties in relation to the obtained microstructure. A significant suppression of martensite transformation by the obtained microstructure is observed. The thermomechanical tests show that the advantageous properties of both grain refinement and precipitation hardening are combined in the developed materials, resulting in superior shape memory characteristics and stability of pseudoelasticity. It is concluded that introducing nanoscaled Ni4Ti3 precipitates into small grains is a new approach to improve the functional properties of NiTi shape memory alloys. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000347017800021 | Publication Date | 2014-10-04 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 51 | Open Access | |
Notes | Fwo | Approved | Most recent IF: 5.301; 2015 IF: 4.465 | ||
Call Number | c:irua:120469 | Serial | 824 | ||
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Author | Pollefeyt, G.; Meledin, A.; Pop, C.; Ricart, S.; Hühne, R.; Van Tendeloo, G.; Van Driessche, I. | ||||
Title | Chemical stability of YBiO3 buffer layers for implementation in YBa2Cu3O7-δ coated conductors | Type | A1 Journal article | ||
Year | 2015 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 100 | Issue | 100 | Pages | 224-231 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | In this work, the chemical and microstructural stability of YBiO3 buffer layers during the growth of YBa2Cu3O7-δ (YBCO) was studied. The superconducting YBCO films were deposited via both Pulsed Laser Deposition as well as Chemical Solution Deposition. Although excellent superconducting properties are obtained in both cases, self-field critical current densities of 3.6 and 1.2 MA/cm2 respectively, chemical instability of the YBiO3 buffer layer is observed. An elaborate transmission electron microscopy study showed that in the case of vacuum deposited YBCO, the YBiO3 becomes unstable and Bi2O3 sublimates out of the architecture. Due to this structural instability, an intermediate Y2O3 layer is obtained which maintains it microstructural orientation relation with the substrate and acts as growth template for YBCO. For chemical solution deposited YBCO, reaction of YBCO with the YBiO3 buffer layer is observed, leading to large grains of YBa2BiO6 which are pushed towards the surface of the films and strongly reduce the superconducting properties. Upon using high growth temperatures for the superconducting layer, these secondary phases decompose, which subsequently leads to Bi2O3 sublimation and a textured YBCO film which directly nucleated onto the LaAlO3 single crystal substrate. Hence, this electron microscopy study indicates that bismuth-based buffer layers systems are not suitable for implementation in coated conductors. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000362616400023 | Publication Date | 2015-08-29 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record | |
Impact Factor | 5.301 | Times cited | Open Access | ||
Notes | One of the authors (G.P.) would like to thank the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT) for funding. Part of this work was performed within the framework of the EuroTapes project (FP7-NMP.2011.2.2-1 Grant No. 280438), funded by the European Union. | Approved | Most recent IF: 5.301; 2015 IF: 4.465 | ||
Call Number | c:irua:128757 | Serial | 3953 | ||
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Author | Shi, H.; Frenzel, J.; Martinez, G.T.; Van Rompaey, S.; Bakulin, A.; Kulkova, A.; Van Aert, S.; Schryvers, D. | ||||
Title | Site occupation of Nb atoms in ternary Ni-Ti-Nb shape memory alloys | Type | A1 Journal article | ||
Year | 2014 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 74 | Issue | Pages | 85-95 | |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Nb occupancy in the austenite B2-NiTi matrix and Ti2Ni phase in NiTiNb shape memory alloys was investigated by aberration-corrected scanning transmission electron microscopy and precession electron diffraction. In both cases, Nb atoms were found to prefer to occupy the Ti rather than Ni sites. A projector augmented wave method within density functional theory was used to calculate the atomic and electronic structures of the austenitic B2-NiTi matrix phase and the Ti2Ni precipitates both with and without addition of Nb. The obtained formation energies and analysis of structural and electronic characteristics explain the preference for Ti sites for Nb over Ni sites. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000338621400009 | Publication Date | 2014-05-08 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 21 | Open Access | |
Notes | Approved | Most recent IF: 5.301; 2014 IF: 4.465 | |||
Call Number | UA @ lucian @ c:irua:118334 | Serial | 3028 | ||
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Author | Tirumalasetty, G.K.; van Huis, M.A.; Kwakernaak, C.; Sietsma, J.; Sloof, W.G.; Zandbergen, H.W. | ||||
Title | Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel | Type | A1 Journal article | ||
Year | 2012 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 60 | Issue | 3 | Pages | 1311-1321 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Uniaxial straining experiments were performed on a rolled and annealed Si-alloyed TRIP (transformation-induced plasticity) steel sheet in order to assess the role of its microstructure on the mechanical stability of austenite grains with respect to martensitic transformation. The transformation behavior of individual metastable austenite grains was studied both at the surface and inside the bulk of the material using electron back-scattered diffraction (EBSD) and X-ray diffraction (XRD) by deforming the samples to different strain levels up to about 20%. A comparison of the XRD and EBSD results revealed that the retained austenite grains at the surface have a stronger tendency to transform than the austenite grains in the bulk of the material. The deformation-induced changes of individual austenite grains before and after straining were monitored with EBSD. Three different types of austenite grains can be distinguished that have different transformation behaviors: austenite grains at the grain boundaries between ferrite grains, twinned austenite grains, and embedded austenite grains that are completely surrounded by a single ferrite grain. It was found that twinned austenite grains and the austenite grains present at the grain boundaries between larger ferrite grains typically transform first, i.e. are less stable, in contrast to austenite grains that are completely embedded in a larger ferrite grain. In the latter case, straining leads to rotations of the harder austenite grain within the softer ferrite matrix before the austenite transforms into martensite. The analysis suggests that austenite grain rotation behavior is also a significant factor contributing to enhancement of the ductility. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000301157900054 | Publication Date | 2011-12-19 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 80 | Open Access | |
Notes | Approved | Most recent IF: 5.301; 2012 IF: 3.941 | |||
Call Number | UA @ lucian @ c:irua:97210 | Serial | 630 | ||
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Author | Colla, M.-S.; Wang, B.; Idrissi, H.; Schryvers, D.; Raskin, J.-P.; Pardoen, T. | ||||
Title | High strength-ductility of thin nanocrystalline palladium films with nanoscale twins : on-chip testing and grain aggregate model | Type | A1 Journal article | ||
Year | 2012 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 60 | Issue | 4 | Pages | 1795-1806 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | The mechanical behaviour of thin nanocrystalline palladium films with an ∼30 nm in plane grain size has been characterized on chip under uniaxial tension. The films exhibit a large strain hardening capacity and a significant increase in the strength with decreasing thickness. Transmission electron microscopy has revealed the presence of a moderate density of growth nanotwins interacting with dislocations. A semi-analytical grain aggregate model is proposed to investigate the impact of different contributions to the flow behaviour, involving the effect of twins, of grain size and of the presence of a thin surface layer. This model provides guidelines to optimizing the strength/ductility ratio of the films. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000301989500035 | Publication Date | 2012-02-02 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 38 | Open Access | |
Notes | Iap | Approved | Most recent IF: 5.301; 2012 IF: 3.941 | ||
Call Number | UA @ lucian @ c:irua:94213 | Serial | 1465 | ||
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Author | Tirumalasetty, G.K.; van Huis, M.A.; Fang, C.M.; Xu, Q.; Tichelaar, F.D.; Hanlon, D.N.; Sietsma, J.; Zandbergen, H.W. | ||||
Title | Characterization of NbC and (Nb, Ti)N nanoprecipitates in TRIP assisted multiphase steels | Type | A1 Journal article | ||
Year | 2011 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 59 | Issue | 19 | Pages | 7406-7415 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Multiphase steels utilising composite strengthening may be further strengthened via grain refinement or precipitation by the addition of microalloying elements. In this study a Nb microalloyed steel comprising martensite, bainite and retained austenite has been studied. By means of transmission electron microscopy (TEM) we have investigated the size distribution and the structural properties of (Nb, Ti)N and NbC precipitates, their occurrence in the various steel phases, and their relationship with the Fe matrix. (Nb, Ti)N precipitates were found in ferrite, martensite, and bainite, while NbC precipitates were found only in ferrite. All NbC precipitates were found to be small (520 nm in size) and to have a face centred cubic (fcc) crystal structure with lattice parameter a = 4.36 ± 0.05 Å. In contrast, the (Nb, Ti)N precipitates were found to have a broader size range (5150 nm) and to have a fcc crystal structure with lattice parameter a = 8.09 ± 0.05 Å. While the NbC precipitates were found to be randomly oriented, the (Nb, Ti)N precipitates have a well-defined NishiyamaWasserman orientation relationship with the ferrite matrix. An analysis of the lattice mismatch suggests that the latter precipitates have a high potential for effective strengthening. Density functional theory calculations were performed for various stoichiometries of NbCx and NbxTiyNz phases and the comparison with experimental data indicates that both the carbides and nitrides are deficient in C and N content. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000296405200026 | Publication Date | 2011-09-29 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 58 | Open Access | |
Notes | Approved | Most recent IF: 5.301; 2011 IF: 3.755 | |||
Call Number | UA @ lucian @ c:irua:93297 | Serial | 328 | ||
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Author | Malard, B.; Pilch, J.; Sittner, P.; Delville, R.; Curfs, C. | ||||
Title | In situ investigation of the fast microstructure evolution during electropulse treatment of cold drawn NiTi wires | Type | A1 Journal article | ||
Year | 2011 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 59 | Issue | 4 | Pages | 1542-1556 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Microstructural changes taking place during the heat treatment of cold-worked NiTi alloy are of key interest in shape memory alloy technology, since they are responsible for setting the austenite shape and functional properties of the heat-treated alloy. In this work, microstructural evolution during non-conventional electropulse heat treatment of thin NiTi filaments was investigated in a unique high-speed in situ synchrotron X-ray diffraction experiment with simultaneous evaluation of the tensile force and electrical resistivity of the treated wire. The in situ results provide direct experimental evidence on the evolution of the internal stress and density of defects during fast heating from 20 °C to ∼700 °C. This evidence is used to characterize a sequence of dynamic recovery and recrystallization processes responsible for the microstructure and superelastic functional property changes during the electropulse treatments. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000287265100023 | Publication Date | 2010-12-11 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 48 | Open Access | |
Notes | Approved | Most recent IF: 5.301; 2011 IF: 3.755 | |||
Call Number | UA @ lucian @ c:irua:98372 | Serial | 1583 | ||
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Author | Cao, S.; Nishida, M.; Schryvers, D. | ||||
Title | Quantitative three-dimensional analysis of Ni4Ti3 precipitate morphology and distribution in polycrystalline Ni-Ti | Type | A1 Journal article | ||
Year | 2011 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 59 | Issue | 4 | Pages | 1780-1789 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | The three-dimensional size, morphology and distribution of Ni4Ti3 precipitates in a Ni50.8Ti49.2 polycrystalline shape memory alloy with a heterogeneous microstructure have been investigated using a focused ion beam/scanning electron microscopy slice-and-view procedure. The mean volume, central plane diameter, thickness, aspect ratio and sphericity of the precipitates in the grain interior as well as near to the grain boundary were measured and/or calculated. The morphology of the precipitates was quantified by determining the equivalent ellipsoids with the same moments of inertia and classified according to the Zingg scheme. Also, the pair distribution functions describing the three-dimensional distributions were obtained from the coordinates of the precipitate mass centres. Based on this new data it is suggested that the existence of the heterogeneous microstructure could be due to a very small concentration gradient in the grains of the homogenized material and that the resulting multistage martensitic transformation originates in strain effects related to the size of the precipitates and scale differences of the available B2 matrix in between the precipitates. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000287265100045 | Publication Date | 2010-12-20 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 34 | Open Access | |
Notes | Fwo | Approved | Most recent IF: 5.301; 2011 IF: 3.755 | ||
Call Number | UA @ lucian @ c:irua:85533 | Serial | 2766 | ||
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Author | Chen, X.; Cao, S.; Ikeda, T.; Srivastava, V.; Snyder, G.J.; Schryvers, D.; James, R.D. | ||||
Title | A weak compatibility condition for precipitation with application to the microstructure of PbTe-Sb2Te3 thermoelectrics | Type | A1 Journal article | ||
Year | 2011 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 59 | Issue | 15 | Pages | 6124-6132 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | We propose a weak condition of compatibility between phases applicable to cases exhibiting full or partial coherence and Widmanstätten microstructure. The condition is applied to the study of Sb2Te3 precipitates in a PbTe matrix in a thermoelectric alloy. The weak condition of compatibility predicts elongated precipitates lying on a cone determined by a transformation stretch tensor. Comparison of this cone with the long directions of precipitates determined by a slice-and-view method of scanning electron microscopy combined with focused ion beam sectioning shows good agreement between theory and experiment. A further study of the morphology of precipitates by the Eshelby method suggests that interfacial energy also plays a role and gives an approximate value of interfacial energy per unit area of 250 dyn cm−1. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000294086900026 | Publication Date | 2011-07-22 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 8 | Open Access | |
Notes | Approved | Most recent IF: 5.301; 2011 IF: 3.755 | |||
Call Number | UA @ lucian @ c:irua:92388 | Serial | 3911 | ||
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Author | Delville, R.; Malard, B.; Pilch, J.; Schryvers, D. | ||||
Title | Microstructure changes during non-conventional heat treatment of thin NiTi wires by pulsed electric current studied by transmission electron microscopy | Type | A1 Journal article | ||
Year | 2010 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 58 | Issue | 13 | Pages | 4503-4515 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Transmission electron microscopy, electrical resistivity measurements and mechanical testing were employed to investigate the evolution of microstructure and functional superelastic properties of 0.1 mm diameter as-drawn NiTi wires subjected to a non-conventional heat treatment by controlled electric pulse currents. This method enables a better control of the recovery and recrystallization processes taking place during the heat treatment and accordingly a better control on the final microstructure. Using a stepwise approach of millisecond pulse annealing, it is shown how the microstructure evolves from a severely deformed state with no functional properties to an optimal nanograined microstructure (2050 nm) that is partially recovered through polygonization and partially recrystallized and that has the best functional properties. Such a microstructure is highly resistant against dislocation slip upon cycling, while microstructures annealed for longer times and showing mostly recrystallized grains were prone to dislocation slip, particularly as the grain size exceeds 200 nm. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000279787100020 | Publication Date | 2010-06-02 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 110 | Open Access | |
Notes | Multimat; FWO IAA | Approved | Most recent IF: 5.301; 2010 IF: 3.791 | ||
Call Number | UA @ lucian @ c:irua:83279 | Serial | 2062 | ||
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Author | Idrissi, H.; Renard, K.; Ryelandt, L.; Schryvers, D.; Jacques, P.J. | ||||
Title | On the mechanism of twin formation in FeMnC TWIP steels | Type | A1 Journal article | ||
Year | 2010 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
Volume | 58 | Issue | 7 | Pages | 2464-2476 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Although it is well known that FeMnC TWIP steels exhibit high work-hardening rates, the elementary twinning mechanisms controlling the plastic deformation of these steels have still not been characterized. The aim of the present study is to analyse the extended defects related to the twinning occurrence using transmission electron microscopy. Based on these observations, the very early stage of twin nucleation can be attributed to the pole mechanism with deviation proposed by Cohen and Weertman or to the model of Miura, Takamura and Narita, while the twin growth is controlled by the pole mechanism proposed by Venables. High densities of sessile Frank dislocations are observed within the twins at the early stage of deformation, which can affect the growth and the stability of the twins, but also the strength of these twins and their interactions with the gliding dislocations present in the matrix. This experimental evidence is discussed and compared to recent results in order to relate the defects analysis to the macroscopic behaviour of this category of material. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Oxford | Editor | ||
Language | Wos | 000276523200018 | Publication Date | 2010-01-25 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1359-6454; | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.301 | Times cited | 244 | Open Access | |
Notes | Iap | Approved | Most recent IF: 5.301; 2010 IF: 3.791 | ||
Call Number | UA @ lucian @ c:irua:82270 | Serial | 2441 | ||
Permanent link to this record |