Phase field simulations of coupled phase transformations in ferroelastic-ferroelastic nanocomposites

TL;DR

This study employs phase field simulations to explore how coupled phase transformations in ferroelastic nanocomposites lead to unique microstructures and transformation behaviors influenced by temperature, layer thickness, and crystal structure.

Contribution

It reveals that elastic coupling in ferroelastic nanocomposites can induce phase transformations above normal temperatures and produce diverse microstructures not seen in bulk materials.

Findings

Phase transformation can occur above critical temperature in nanocomposites.

Microstructure diversity depends on temperature, layer thickness, and crystal structure.

Twin periodicity varies significantly with geometry.

Abstract

We use phase field simulations to study composites made of two different ferroelastics (e.g., two types of martensite). The deformation of one material due to a phase transformation can elastically affect the other constituent and induce it to transform as well. We show that the phase transformation can then occur above its normal critical temperature and even higher above this temperature in nanocomposites than in bulk composites. Microstructures depend on temperature, on the thickness of the layers, and on the crystal structure of the two constituents -- certain nanocomposites exhibit a great diversity of microstructures not found in bulk composites. Also, the periodicity of the martensite twins may vary over 1 order of magnitude based on geometry. keywords: Ginzburg-Landau, martensitic transformation, multi-ferroics, nanostructure, shape-memory alloy