A structural phase transformation is the transformation of a crystal structure due to the displacement of atoms, with no diffusion and no changes in the relative positions. These transformations are often induced by changes in temperature; however stress, electromagnetic fields and other loads can also induce transformations. The schematic below shows a cubic to tetragonal transformation. The crystal is cubic at high temperature and tetragonal at low temperature. Due to the symmetry of the cube stretching along any of its axes, there are 3 possible variants or twins at low temperature.

Abstract 

We study the kinetics of phase transformations in solids using the peridynamic formulation of continuum mechanics. The peridynamic theory is a nonlocal formulation that does not involve spatial derivatives, and is a powerful tool to study defects such as cracks and interfaces.