Correlations of non-affine displacements in metallic glasses through the yield transition

Abstract

We study correlations of non-affine displacements during simple shear deformation of Cu-Zr bulk metallic glasses in molecular dynamics calculations. In the elastic regime, our calculations show exponential correlation with a decay length that we interpret as the size of a shear transformation zone in the elastic regime. This correlation length becomes system-size dependent beyond the yield transition as our calculation develops a shear band, indicative of a diverging length scale. We discuss these observations in the context of a recent proposition of yield as a first-order phase transition.

Shear Band Formation in Amorphous Materials under Oscillatory Shear Deformation

“…This definition was first introduced by Falk and Langer and used to identify accurately the location of shear transformations in strained disordered solids [40]. More recently, the spatiotemporal analysis of nonaffine displacements was applied to investigate shear band formation in steadily [12][13][14]42] and periodically [21,23,25,29,30,34] driven amorphous solids, as well as the structural relaxation in thermally cycled [43,44] and elastostatically loaded [45] glasses. Interestingly, the accumulation of atoms with large nonaffine displacements along the xy plane, shown in Fig.…”

“…It has long been recognized that localized plastic events in deformed amorphous materials involve collective rearrangements of small clusters of atoms, or shear transformations [5,6]. In recent years, the processes of shear band initiation and propagation have been extensively studied at the atomic level during startup uniaxial [7][8][9][10][11] and shear [12][13][14] deformation with a constant strain rate. While the initiation of a shear band typically occurs at a free surface during tension or compression, the transition to plastic flow in a sheared periodic domain involves the formation of a percolating cluster of mobile regions at the critical strain [12].…”

A delayed yielding transition in mechanically annealed binary glasses at finite temperature

“…where ∆t is the time interval between successive positions of N i atoms, and the sum is taken over nearest neighbors of the i-th atom [38]. The spatiotemporal analysis on nonaffine displacements of atoms was recently carried out to describe irreversible dynamics in binary glasses under various loading conditions, namely, periodic [12,14,16,18,19,25,27,32] and startup continuous [39][40][41][42][43] shear deformation, tension-compression loading [20,29],…”

Shear band healing in amorphous materials by small-amplitude oscillatory shear deformation

“…(3) was originally introduced by Falk and Langer in order to accurately detect the localized shear transformations that involved swift rearrangements of small groups of atoms in driven disordered solids [47]. In the last few years, this method was widely used to study the collective, irreversible dynamics of atoms in binary glasses subjected to time periodic [16,18,20,22,23,29,31,32,35,37] and startup continuous [48][49][50][51][52][53][54] shear deformation, tension-compression cyclic loading [24,33], prolonged elastostatic compression [55,56], creep [57] and thermal cyclic loading [58][59][60][61][62].…”