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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. pdf  url
doi  openurl
  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.  
  Address  
  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 (down) 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. pdf  url
doi  openurl
  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.  
  Address  
  Corporate Author Thesis  
  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 (down) 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. pdf  doi
openurl 
  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.  
  Address  
  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 (down) Most recent IF: 5.301  
  Call Number UA @ lucian @ c:irua:142398 Serial 4645  
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Author Cautaerts, N.; Delville, R.; Stergar, E.; Schryvers, D.; Verwerft, M. pdf  url
doi  openurl
  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.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000456902800008 Publication Date 2018-10-11  
  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 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 (down) 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. pdf  doi
openurl 
  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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  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 (down) 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. pdf  doi
openurl 
  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.  
  Address  
  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 (down) Most recent IF: 5.301  
  Call Number UA @ admin @ c:irua:164641 Serial 6295  
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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. url  doi
openurl 
  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.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000670077800004 Publication Date 2021-05-12  
  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 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 (down) 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. url  doi
openurl 
  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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000706867800004 Publication Date 2021-08-19  
  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 Open Access OpenAccess  
  Notes Approved (down) 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. pdf  url
doi  openurl
  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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000705535300005 Publication Date 2021-09-12  
  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 OpenAccess  
  Notes Approved (down) Most recent IF: 5.301  
  Call Number UA @ admin @ c:irua:182528 Serial 6884  
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