Incorporating a soft ordered phase into an amorphous configuration enhances its uniform plastic deformation under shear

TL;DR

Introducing a soft ordered phase into amorphous materials via molecular dynamics simulations improves the uniformity of plastic deformation under shear, potentially preventing shear localization and shear band formation.

Contribution

This study demonstrates that embedding a soft ordered phase within amorphous materials enhances deformation uniformity, a novel approach to controlling shear behavior.

Findings

Inhomogeneous mixtures deform more uniformly than homogeneous ones.

Softness of the ordered phase influences deformation behavior.

Structural inhomogeneity and phase softness jointly improve shear response.

Abstract

Amorphous materials of homogeneous structures usually suffer from nonuniform deformation under shear, which can develop into shear localization and eventually destructive shear band. One approach to tackle this issue is to introduce an inhomogeneous structure containing more than one phase, which can reduce the local nonuniform shear deformation and hinder its percolation throughout the system. Using thermostated molecular dynamics (MD) simulations, we compare the deformation behavior between a homogeneous amorphous mixture of bidisperse disc particles, interacting via an n-6 Lennard-Jones potential of tunable softness, with an inhomogeneous one containing an evenly-distributed ordered phase. We change the population ratio of large to small particles to create a homogeneous or an inhomogeneous mixture, where the softness of a chosen phase can be manually adjusted by specifying n of the interparticle potential. Results of applying extensive quasistatic shear on the prepared mixtures reveal that the inhomogeneous amorphous mixture containing a soft ordered phase overall deforms more uniformly than the homogeneous one, which indicates that both the structure inhomogeneity and the inter-phase softness variance play important roles in enhancing the uniformity of the plastic deformation under shear.