Browsing by Author "Almer, JD"

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    Direct, time-resolved in-situ observation of dynamic recyrstallization and related phenomena in the bulk of zirconium alloy
    (Australian Institute of Physics, 2009-02-04) Liss, KD; Garbe, U; Schambron, T; Almer, JD; Li, HJ; Yan, K; Dippenaar, RJ
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    In situ observation of dynamic recrystallization in the bulk of zirconium alloy
    (Wiley-VCH Verlag Berlin, 2009-08) Liss, KD; Garbe, U; Li, HJ; Schambron, T; Almer, JD; Yan, K
    Dynamic recrystallization and related effects have been followed in situ and in real time while a metal undergoes rapid thermo-mechanical processing. Statistics and orientation correlations of embedded/bulk material grains were deduced from two-dimensional X-ray diffraction patterns and give deep insight into the formation of the microstructure. Applications are relevant in materials design, simulation, and in geological systems. © 2009, Wiley-VCH Verlag Berlin
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    On the atomic anisotropy of thermal expansion in bulk metallic glass
    (Wiley-Blackwell, 2011-09-01) Qu, DD; Liss, KD; Yan, K; Reid, M; Almer, JD; Wang, Y; Liao, XZ; Shen, J
    Glass transition temperature and plastic yield strength are known to be correlated in metallic glasses. We have observed by in situ synchrotron high energy X-ray diffraction anisotropy of the thermal expansion behavior in the nearest neighbor and second nearest neighbor atomic distances in the building blocks of Zr-Cu-Ni-Al based bulk metallic glass, leading inevitably to shear. Mechanical yielding of the latter on the atomic scale leads to the glass transition and the increase of the free volume. These experimental results uncover the mechanism, how glass transition and yield strength are linked. © 2011, Wiley-Blackwell.
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    Structural origins for the high plasticity of a Zr-Cu-Ni-Al bulk metallic glass
    (Pergamon-Elsevier Science Ltd, 2012-09-11) Qu, DD; Liss, KD; Sun, YJ; Reid, M; Almer, JD; Yan, K; Wang, Y; Liao, XZ; Shen, J
    The structural origins for the high plasticity of a Zr(53)Cu(18.7)Ni(12)Al(16.3) (at.%) bulk metallic glass are explored. Under plastic flow conditions, in situ synchrotron high-energy X-ray diffraction reveals that the atomic strain saturates to the closest packing in the longitudinal direction of the applied load while atoms yield in the transverse plane. Scanning electron microscopy investigation reveals that global plasticity benefits from abundant shear band multiplication and interactions. Atomic level flows are seen to accompany profuse shear bands. The plasticity enhancement of this metallic glass benefits from such atomic level flows. Atomic level flow facilitates the activation of shear transformation zones that further self-assemble to promote shear band multiplication. On the other hand, it also mitigates the shear band propagation that prevents catastrophic shear band extension. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. © 2012, Elsevier Ltd.