“In Situ Quantitative Tensile Testing of Antigorite in a Transmission Electron Microscope”. Idrissi H, Samaee V, Lumbeeck G, Werf T, Pardoen T, Schryvers D, Cordier P, Journal Of Geophysical Research-Solid Earth 125 (2020). http://doi.org/10.1029/2019JB018383
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.9
DOI: 10.1029/2019JB018383
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“Novel class of nanostructured metallic glass films with superior and tunable mechanical properties”. Ghidelli M, Orekhov A, Bassi AL, Terraneo G, Djemia P, Abadias G, Nord M, Béché, A, Gauquelin N, Verbeeck J, Raskin J-p, Schryvers D, Pardoen T, Idrissi H, Acta Materialia , 116955 (2021). http://doi.org/10.1016/j.actamat.2021.116955
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.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 27
DOI: 10.1016/j.actamat.2021.116955
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“Tailoring Mechanical Properties of a-C:H:Cr Coatings”. Bagherpour A, Baral P, Colla M-S, Orekhov A, Idrissi H, Haye E, Pardoen T, Lucas S, Coatings 13, 2084 (2023). http://doi.org/10.3390/coatings13122084
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.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
DOI: 10.3390/coatings13122084
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