Dipolar and quadrupolar characteristics of shear transformation in two dimensional metallic glasses

RH Shi and YC Wu and F Shuang and ZW Zhang, MATERIALS TODAY COMMUNICATIONS, 34, 105389 (2023).

DOI: 10.1016/j.mtcomm.2023.105389

Localized shear transformation (ST), a fundamental and ubiquitous plastic phenomenon in metallic glasses (MGs), is still an enigma because of intrinsic entangling of shear, dilatation, and rotation. Here, to unveil this mystery, we formulate a theoretical protocol based on quadrupolar Eshelby inclusion supplemented by simulations of two- dimensional (2D) Lennard-Jones MGs and wavenumber spectrum analysis, revealing that only STs of pure shear or tension are well-known quadrupoles, whereas STs of torsion or simple shear exhibit strongly dipolar characteristics, which are the physical-mathematical explanations for shear-induced dilatation and shearvortex coupling. Initial ST events are quadrupoles including shear and dilatation. As spatiotemporal coupling intensifies, ST is gradually dominated by dipoles and vortices, contributed to self-assembly and percolation. Our findings reinforce the inherent correlation between evolution of quadrupolar/dipolar characteristics and plastic deformation of MGs, providing fundamental understandings for localized amorphous flow events.

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