Observation of the two way shape memory effect in an atomistic model of martensitic transformation

TL;DR

This paper demonstrates the development of the two-way shape memory effect in a 2D atomistic model of martensitic transformation, highlighting the roles of retained martensite and dislocation orientations in polycrystalline and single crystal samples.

Contribution

It extends previous models to describe the more subtle two-way shape memory effect, linking it to microstructural features like retained martensite and dislocation orientations.

Findings

Two-way shape memory effect observed in polycrystalline samples due to retained martensite.

Single crystal samples show the effect linked to specific dislocation orientations.

The model reproduces key features of martensitic shape memory phenomena.

Abstract

We study a system of classical particles in two dimensions interacting through an isotropic pair potential that displays a martensitic phase transition between a triangular and a rhomboidal structure upon the change of a single parameter. Previously it was shown that this potential is able to reproduce the shape memory effect and super-elasticity, among other well known features of the phenomenology of martensites. Here we extend those previous studies and describe the development of the more subtle two-way shape memory effect. We show that in a poly-crystalline sample, the effect can be associated to the existence of retained martensite within the austenite phase. We also study the case of a single crystal sample where the effect is associated to particular orientations of the dislocations, either induced by training or by an ad hoc construction of a starting sample.