Elastoplastic model for the dynamics of solid-solid transformations : role of non-affine deformation in microstructure selection

TL;DR

This paper investigates how non-affine deformations influence microstructure selection during solid-solid transformations, using molecular dynamics simulations and an elastoplastic model to understand the dynamics and predict microstructure outcomes.

Contribution

It introduces an elastoplastic model coupling elastic strain and non-affine deformation, capturing microstructure selection mechanisms in solid-state transformations.

Findings

Transient non-affine zones are crucial for microstructure evolution.

The elastoplastic model reproduces MD simulation features.

A dynamical phase diagram predicts microstructure outcomes.

Abstract

We study the nucleation dynamics of a model solid state transformation and the criterion for microstructure selection using a molecular dynamics (MD) simulation. Our simulations show a range of microstructures depending on the depth of quench. We closely follow the dynamics of the solid and find that transient {\em non-affine zones} (NAZ) are created at and evolve with the rapidly moving transformation front. The dynamics of these plastic regions determines the selection of microstructure. We formulate an {\it elastoplastic model} which couples the elastic strain to the non-affine deformation, and recover all the qualitative features of the MD simulation. Using this model, we construct a dynamical phase diagram for microstructure selection, in addition to making definite testable predictions.