Finite Element Analysis of Phase Transformation Dynamics in Shape Memory Alloys with a Consistent Landau-Ginzburg Free Energy Model

Abstract

The Landau theory of phase transition has been successfully applied to solve a number of important problems in the dynamics of martensitic phase transformations in alloys. On the other hand, although a precise mathematical description of the microstructures is known within the framework of Cauchy-Born hypothesis, its discrete version is not well elucidated in the literature, especially for multivariant transformations in three-dimensional samples. A major reason for such a situation lies with computational difficulties connected with quasi-convexity of the associated minimization problem. In this paper we develop a Landau-Ginzburg free energy model for dynamic problems of phase transformations and show a possible link of the developed framework with the continuum description of phase transformations. We demonstrate how the precise description of compatible microstructures in the phase-field model can be used in computational finite element models. The developed framework is sufficiently general to be applied to different types of phase transforming alloys and under general thermo-mechanical loadings. We exemplify the developed technique and its finite element implementation on cubic to tetragonal transformations.

Keywords:

• austenite
• martensite
• transformation
• microstructure
• free energy
• finite element