Crystal nucleation and cluster-growth kinetics in a model glass under shear

TL;DR

This study uses molecular dynamics simulations to analyze how shear strain influences crystal nucleation and growth in a model metallic glass, revealing nonmonotonic strain rate effects and developing a kinetic model based on classical theories.

Contribution

It introduces a comprehensive kinetic model for shear-induced crystallization in metallic glasses, integrating nucleation, growth, and strain effects within the KJMA framework.

Findings

Nucleation and growth follow a transient induction regime.

Critical cluster size and lag-time are quantified.

Crystallization kinetics show nonmonotonic strain rate dependence.

Abstract

Crystal nucleation and growth processes induced by an externally applied shear strain in a model metallic glass are studied by means of nonequilibrium molecular dynamics simulations, in a range of temperatures. We observe that the nucleation-growth process takes place after a transient, induction regime. The critical cluster size and the lag-time associated with this induction period are determined from a mean first-passage time analysis. The laws that describe the cluster growth process are studied as a function of temperature and strain rate. A theoretical model for crystallization kinetics that includes the time dependence for nucleation and cluster growth is developed within the framework of the Kolmogorov-Johnson-Mehl-Avrami scenario and is compared with the molecular dynamics data. Scalings for the cluster growth laws and for the crystallization kinetics are also proposed and tested. The observed nucleation rates are found to display a nonmonotonic strain rate dependency.