Phonon Theory of Martensitic Transformation Precursors

TL;DR

This paper develops a phonon-based theoretical framework to explain precursor phenomena in martensitic transformations, addressing structural and thermal anomalies through phonon behavior and symmetry breaking.

Contribution

It extends Grüneisen theory to include deformation-dependent phonons, providing a novel explanation for pre-martensitic phenomena and anomalies.

Findings

Reveals spontaneous symmetry breaking in pre-martensitic phases

Explains pre-transitional anomalies in cubic crystals

Describes phonon domains and tweed structures

Abstract

A phonon theory of precursor phenomena in martensitic phase transformations is developed. Extending Gr\"uneisen theory of thermal expansion, this theory addresses the effects of deformation-dependent low-energy phonons on the structural, thermal, and elastic behaviors of pre-martensitic cubic crystals that undergo incomplete phonon softening. It reveals spontaneous symmetry breaking, pre-martensitic transformation, phonon domains, and tweed structure. The theory naturally explains the ubiquitous pre-transitional anomalies that are difficult to explain from conventional phase transition theories.