Sustainable steady-state serrated flow induced by modulating deformation sequence in bulk metallic glass

WH Ryu and WS Ko and H Isano and R Yamada and H Ahn and GH Yoo and KN Yoon and ES Park and J Saida, JOURNAL OF ALLOYS AND COMPOUNDS, 946, 169308 (2023).

DOI: 10.1016/j.jallcom.2023.169308

Herein, we systematically investigate the compressive plasticity and shear band (SB) behavior of the Zr-based bulk metallic glasses (BMG) with different Poisson's ratio and aspect ratios/contact friction coupling. First, using experimental data and MD simulation we clearly show that a lower contact friction decreases the stress concentration to promote SB distribution and that a smaller aspect ratio increases the probability of SB intersection to improve global plasticity. Secondly, we propose three stages of plastic flow in BMGs through quantitative analysis of serrated flow: (stage I) apparent hardening region with the stochastic serrated flow, (stage II) constant yielding region with the steady-state serrated flow, (stage III) macroscopic softening region with the confined serrated flow. It is confirmed that the plastic flow of BMGs is made by different combinations of these stages. Note that the aspect ratio as well as Poisson's ratio has a greater effect on the variation of plastic flow compared to the friction conditions. Finally, we can propose a three-dimensional map of plastic flow in Zr-based BMGs reflecting the key multi-variables for SB behavior of (Poisson's ratio)-(aspect ratio)-(contact friction), which can explain how to stabilize steady-state serrated flow of stage II (or destabilize macroscopic softening of stage III) by simultaneously considering the in-fluence of the multi-variables. Indeed, we carefully discuss how to design BMG deformable like ductile crystalline alloys. Our studies pave the way for the development of sustainable BMGs with a predictable deformation behavior by tailoring multi-variables of SB behavior.(c) 2023 Published by Elsevier B.V.

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