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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. |
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Title |
Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films |
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A1 Journal article |
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Year |
2016 |
Publication |
Acta materialia |
Abbreviated Journal |
Acta Mater |
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Volume |
111 |
Issue |
111 |
Pages |
253-261 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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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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Wos |
000375812100027 |
Publication Date |
2016-04-06 |
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Edition |
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ISSN |
1359-6454 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.301 |
Times cited |
14 |
Open Access |
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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 |
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Call Number |
c:irua:132678 |
Serial |
4054 |
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Author |
Lumbeeck, G.; Idrissi, H.; Amin-Ahmadi, B.; Favache, A.; Delmelle, R.; Samaee, V.; Proost, J.; Pardoen, T.; Schryvers, D. |
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Title |
Effect of hydriding induced defects on the small-scale plasticity mechanisms in nanocrystalline palladium thin films |
Type |
A1 Journal Article |
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Year |
2018 |
Publication |
Journal Of Applied Physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
124 |
Issue |
22 |
Pages |
225105 |
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Keywords |
A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; |
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Abstract |
Nanoindentation tests performed on nanocrystalline palladium films subjected to hydriding/dehydriding cycles demonstrate a significant softening when compared to the as-received material. The origin of this softening is unraveled by combining in situ TEM nanomechanical testing with automated crystal orientation mapping in TEM and high resolution TEM. The softening is attributed to the presence of a high density of stacking faults and of Shockley partial dislocations after hydrogen loading. The hydrogen induced defects affect the elementary plasticity mechanisms and the mechanical response by acting as preferential sites for twinning/detwinning during deformation. These results are analyzed and compared to previous experimental and simulation works in the literature. This study provides new insights into the effect of hydrogen on the atomistic deformation and cracking mechanisms as well as on the mechanical properties of nanocrystalline thin films and membranes. |
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Wos |
000453254000025 |
Publication Date |
2018-12-14 |
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ISSN |
0021-8979 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
2 |
Open Access |
Not_Open_Access |
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Notes |
This work was supported by the Hercules Foundation under Grant No. AUHA13009, the Flemish Research Fund (FWO) under Grant No. G.0365.15N, and the Flemish Strategic Initiative for Materials (SIM) under the project InterPoCo. Dr. H. Idrissi is mandated by the Belgian National Fund for Scientific Research (FSR-FNRS). We would like to thank Dr. Hadi Pirgazi from UGent for his technical support to process the ACOM data in the OIM Analysis software. |
Approved |
Most recent IF: 2.068 |
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Call Number |
EMAT @ emat @c:irua:155742 |
Serial |
5135 |
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Author |
Bagherpour, A.; Baral, P.; Colla, M.-S.; Orekhov, A.; Idrissi, H.; Haye, E.; Pardoen, T.; Lucas, S. |
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Title |
Tailoring Mechanical Properties of a-C:H:Cr Coatings |
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A1 Journal Article |
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Year |
2023 |
Publication |
Coatings |
Abbreviated Journal |
Coatings |
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13 |
Issue |
12 |
Pages |
2084 |
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Keywords |
A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; |
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Abstract |
The development of coatings with tunable performances is critical to meet a wide range of technological applications each one with different requirements. Using the plasma-enhanced chemical vapor deposition (PECVD) process, scientists can create hydrogenated amorphous carbon coatings doped with metal (a-C:H:Me) with a broad range of mechanical properties, varying from those resembling polymers to ones resembling diamond. These diverse properties, without clear relations between the different families, make the material selection and optimization difficult but also very rich. An innovative approach is proposed here based on projected performance indices related to fracture energy, strength, and stiffness in order to classify and optimize a-C:H:Me coatings. Four different a-C:H:Cr coatings deposited by PECVD with Ar/C2H2 discharge under different bias voltage and pressures are investigated. A path is found to produce coatings with a selective critical energy release rate between 5–125 J/m2 without compromising yield strength (1.6–2.7 GPa) and elastic limit (≈0.05). Finally, fine-tuned coatings are categorized to meet desired applications under different testing conditions. |
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Wos |
001136013600001 |
Publication Date |
2023-12-14 |
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ISSN |
2079-6412 |
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Additional Links |
UA library record; WoS full record |
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Notes |
Walloon region under the PDR FNRS, C 62/5—PDR/OL 33677636 ; Belgian National Fund for Scientific Research, CDR—J.0113.20 ; National Fund for Scientific Reaserch; |
Approved |
Most recent IF: NA |
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Call Number |
EMAT @ emat @c:irua:202390 |
Serial |
8982 |
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Author |
Idrissi, H.; Samaee, V.; Lumbeeck, G.; Werf, T.; Pardoen, T.; Schryvers, D.; Cordier, P. |
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Title |
In Situ Quantitative Tensile Testing of Antigorite in a Transmission Electron Microscope |
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A1 Journal article |
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Year |
2020 |
Publication |
Journal Of Geophysical Research-Solid Earth |
Abbreviated Journal |
J Geophys Res-Sol Ea |
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Volume |
125 |
Issue |
3 |
Pages |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The determination of the mechanical properties of serpentinites is essential toward the understanding of the mechanics of faulting and subduction. Here we present the first in situ tensile tests on antigorite in a transmission electron microscope. A push‐to‐pull deformation device is used to perform quantitative tensile tests, during which force and displacement are measured, while the evolving microstructure is imaged with the microscope. The experiments have been performed at room temperature on 2 × 1 × 0.2 μm3 beams prepared by focused ion beam. The specimens are not single crystals despite their small sizes. Orientation mapping indicated that several grains were well oriented for plastic slip. However, no dislocation activity has been observed even though the engineering tensile stress went up to 700 MPa. We show also that antigorite does not exhibit a purely elastic‐brittle behavior since, despite the presence of defects, the specimens accumulate permanent deformation and did not fail within the elastic regime. Instead, we observe that strain localizes at grain boundaries. All observations concur to show that under these experimental conditions, grain boundary sliding is the dominant deformation mechanism. This study sheds a new light on the mechanical properties of antigorite and calls for further studies on the structure and properties of grain boundaries in antigorite and more generally in phyllosilicates. |
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Wos |
000530895800023 |
Publication Date |
2020-02-20 |
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Edition |
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ISSN |
2169-9313 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.9 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
We thank S. Guillot for having kindly provided us with the two antigorite samples investigated in this study. We acknowledge funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under Grant Agreement 787198—TimeMan. H. Idrissi is mandated by the Belgian National Fund for Scientific Research (FSR‐FNRS). We acknowledge fruitful discussions with A. Baronnet. We thank J. Gasc and an anonymous reviewer for their critical comments. Data (movies of the three in situ deformation experiments) can be downloaded (from https://doi.org/10.5281/zenodo.3583135). |
Approved |
Most recent IF: 3.9; 2020 IF: 3.35 |
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Call Number |
EMAT @ emat @c:irua:167594 |
Serial |
6355 |
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