Coupled analysis of elastic strain energy densities and transformation interfaces in phase field simulations of CuAlNi martensitic transformation

In martensitic transformations, the evolution of elastic fields plays a crucial role in understanding the driving mechanisms of transformation dynamics. This study analyzes the evolution of the local field of elastic strain energy density in conjunction with the transformation microstructure using a multi-field coupled approach. A systematic phase-field simulation is performed to model the martensitic transformation in the ternary alloy CuAlNi. Based on the Gibbs free energy data obtained from microscale analysis, both symmetric and asymmetric free energy potentials are incorporated into the finite-strain phase-field model to explore the fine-tuning of the Landau-based polynomial potential. The effects of modifying the free energy potential on the transformation process are demonstrated through comparative simulations. In the multi-field coupled analysis, two specific types of transformation interfaces, responsible for the majority of interface migration, are coupled with the evolution of two distinct local fields of elastic strain energy density. These fields exhibit significantly higher energy densities than other regions. The detailed coupling mechanisms are explained through the evolution of representative local regions in the phase-field simulation of CuAlNi martensitic transformation, using both symmetric and asymmetric free energy potentials. Notably, the coupling mechanisms are independent of the symmetry of the free energy potential.