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.
Highlights
Homogeneous amorphous materials such as bulk metallic glasses are known for exhibiting superior mechanical properties than their crystalline siblings
We propose a mesoscale model of mixing 2D bidisperse disc particles to study the shear deformation behavior of an amorphous configuration containing an ordered phase using molecular dynamics (MD) simulations
Two equilibrated snapshots of exemplary inhomogeneous and homogeneous amorphous configurations and the rules for interparticle interactions are shown in Fig. 3, where particles in soft-ordered and stiff-amorphous phases are colored in green and orange, respectively
Summary
Homogeneous amorphous materials such as bulk metallic glasses are known for exhibiting superior mechanical properties than their crystalline siblings. Introducing an ordered phase into an amorphous material to make the engineered structure inhomogeneous have been shown to improve their mechanical properties, for example, embedding an isolated and soft crystal phase containing dendrites in a bulk metallic glass matrix to enhance tensile ductility, and distributing polycrystalline metallic alloys within amorphous shells to raise mechanical strength and restrict shear localization.. We propose a mesoscale model of mixing 2D bidisperse disc particles to study the shear deformation behavior of an amorphous configuration containing an ordered phase using molecular dynamics (MD) simulations. Our model shows that introducing an ordered phase into an amorphous phase helps the inhomogeneous system deform more uniformly under shear than a homogeneous single-phased system when the applied shear strain is small.
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