Slip-dominated structural transitions

TL;DR

This paper demonstrates that plastic slip is essential in the transformation mechanism of a square-to-triangular structural transition, revealing the importance of lattice-invariant shears and hidden slip distributions in reconstructive phase changes.

Contribution

It introduces a novel atomistically-informed mesoscopic model to uncover slip distributions and emphasizes the central role of plasticity in phase transformations.

Findings

Plastic slip is crucial in the transformation mechanism.

Hidden slip distributions are revealed behind the product phase.

Lattice invariant shears are central to the transition.

Abstract

We use molecular dynamics to show that plastic slip is a crucial component of the transformation mechanism of a square-to-triangular structural transition. The latter is a stylized analog of many other reconstructive phase transitions. To justify our conclusions we use a novel atomistically-informed mesoscopic representation of the field of lattice distortions in molecular dynamics simulations. Our approach reveals a hidden alternating slip distribution behind the seemingly homogeneous product phase which points to the fact that lattice invariant shears play a central role in this class of phase transformations. While the underlying pattern of anti-parallel displacements may be also interpreted as microscopic shuffling, its precise crystallographic nature strongly suggests the plasticity-centered interpretation.