TY - JOUR
T1 - Heterogeneous structural changes correlated to local atomic order in thermal rejuvenation process of Cu-Zr metallic glass
AU - Wakeda, Masato
AU - Saida, Junji
N1 - Funding Information:
This work was supported by the Japan Society for the Promotion of Science, Grant-in-Aid for [Scientific Research (A) (No. 18H03829), Young Scientists (A) (No. 17H04949)].
Publisher Copyright:
© 2019, © 2019 The Author(s). Published by National Institute for Materials Science in partnership with Taylor & Francis Group.
PY - 2019/12/31
Y1 - 2019/12/31
N2 - In this study, we investigated the atomistic mechanism of structural excitation in a thermal process (thermal rejuvenation) of metallic glass. In a molecular dynamics framework, Cu-Zr metallic glass was rejuvenated by a thermal process composed of an isothermal heat treatment at a temperature above the glass transition temperature Tg, followed by fast cooling. Atomistic analyses of the local rearrangement, potential energy, and geometrical structure revealed structural changes correlating to the local atomic order in the rejuvenation process. In the early stage of the heat treatment for thermal rejuvenation, the structural excitation exhibited spatial heterogeneity at the nanometer scale. More-excited regions (i.e., regions with large atomic non-affine and affine transformations) exhibited low-ordered structures and vice versa, implying that the local structural excitation is significantly correlated with the local atomic order. The structural excitation transitioned from partial to whole as the isothermal process proceeded above Tg. Although rejuvenation decreased the ordered structure, the calculation results suggested the formation of newly ordered local structures and newly disordered local structures correlated to local structural excitations and atomic dynamics in the thermal process. These results indicate that the heterogeneous structure evolution of the rejuvenation process induces a redistribution of the local atomic order in the microstructure of metallic glasses.
AB - In this study, we investigated the atomistic mechanism of structural excitation in a thermal process (thermal rejuvenation) of metallic glass. In a molecular dynamics framework, Cu-Zr metallic glass was rejuvenated by a thermal process composed of an isothermal heat treatment at a temperature above the glass transition temperature Tg, followed by fast cooling. Atomistic analyses of the local rearrangement, potential energy, and geometrical structure revealed structural changes correlating to the local atomic order in the rejuvenation process. In the early stage of the heat treatment for thermal rejuvenation, the structural excitation exhibited spatial heterogeneity at the nanometer scale. More-excited regions (i.e., regions with large atomic non-affine and affine transformations) exhibited low-ordered structures and vice versa, implying that the local structural excitation is significantly correlated with the local atomic order. The structural excitation transitioned from partial to whole as the isothermal process proceeded above Tg. Although rejuvenation decreased the ordered structure, the calculation results suggested the formation of newly ordered local structures and newly disordered local structures correlated to local structural excitations and atomic dynamics in the thermal process. These results indicate that the heterogeneous structure evolution of the rejuvenation process induces a redistribution of the local atomic order in the microstructure of metallic glasses.
KW - 10 Engineering and Structural materials
KW - 106 Metallic materials
KW - 107 Glass and ceramic materials
KW - 400 Modeling / Simulations
KW - Metallic glass
KW - geometrical structure
KW - molecular dynamics
KW - rejuvenation
KW - structural heterogeneity
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U2 - 10.1080/14686996.2019.1624140
DO - 10.1080/14686996.2019.1624140
M3 - Article
AN - SCOPUS:85067599939
VL - 20
SP - 632
EP - 642
JO - Science and Technology of Advanced Materials
JF - Science and Technology of Advanced Materials
SN - 1468-6996
IS - 1
ER -