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| Author | Viart, N.; Sayed Hassan, R.; Ulhaq-Bouillet, C.; Meny, C.; Panissod, P.; Loison, J.L.; Versini, G.; Huber, F.; Pourroy, G.; Verbeeck, J.; Van Tendeloo, G. | ||||
| Title | Oxidation processes at the metal/oxide interface in CoFe2/CoFe2O4 bilayers deposited by pulsed laser deposition | Type | A1 Journal article | ||
| Year | 2006 | Publication | Acta materialia | Abbreviated Journal | Acta Mater |
| Volume | 54 | Issue | 1 | Pages  |
191-196 |
| Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
| Abstract | CoFe2/CoFe2O4 bilayers were made by pulsed laser ablation of a CoFe2 target on Si(I 0 0) substrates. The metallic layer was deposited first, in vacuum. The oxide was then deposited in an oxidizing O-2:N-2 (20:80) atmosphere. Two different procedures were used for the introduction of the oxidizing atmosphere in the deposition chamber: the laser ablation of the target was either stopped (discontinuous deposition process) or maintained (continuous deposition process) during the 20 min necessary for the establishment of the desired O-2:N-2 pressure. In both cases, the different electronegativities of Fe and Co cause an important modification of the Fe/Co ratio at the metal/oxide interface, with a depletion of Fe in the metal region and of Co in the oxide region. In the continuous procedure, the combination of the kinetic energy given by the ablation process to the Fe and Co adatoms with the one they get from their different affinity towards oxidation allows the formation of a low roughness metal/oxide interface with a high (111) preferred orientation of the CoFe2O4 layer, an induced re-crystallisation of the metal layer underneath and an unusual antiferromagnetic metal/oxide magnetic coupling. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. | ||||
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| Publisher | Place of Publication | Oxford | Editor | ||
| Language | Wos | 000233784500021 | Publication Date | 2005-10-15 | |
| 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 | |
| Notes | Approved | Most recent IF: 5.301; 2006 IF: 3.549 | |||
| Call Number | UA @ lucian @ c:irua:56043UA @ admin @ c:irua:56043 | Serial | 2540 | ||
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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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| Publisher | Place of Publication | Editor | |||
| Language | Wos | 000564767000001 | Publication Date | 2020-07-10 | |
| 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 | ; 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 | 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 | 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 | 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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| 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 | 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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| Language | Wos | 000371650300006 | Publication Date | 2016-01-08 | |
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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 | 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 | 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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| Language | Wos | 000394201500003 | Publication Date | 2016-12-02 | |
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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 | 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 | 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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| Publisher | Place of Publication | Oxford | Editor | ||
| Language | Wos | Publication Date | |||
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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 | Open Access | OpenAccess | |
| Notes | Approved | Most recent IF: 5.301 | |||
| Call Number | UA @ lucian @ c:irua:142398 | Serial | 4645 | ||
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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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| Publisher | Place of Publication | Oxford | Editor | ||
| Language | Wos | 000375812100002 | Publication Date | 2016-03-26 | |
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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 | 6 | Open Access | |
| Notes | Approved | Most recent IF: 5.301 | |||
| Call Number | UA @ lucian @ c:irua:133636 | Serial | 4162 | ||
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