Chemo-mechanical multiphase-field modeling: studies on formation of Widmanstätten ferrite and pearlite
Numerical simulations based on phase-field methods render a comprehensive investigation of the interesting and important phenomena accompanying the evolution of microstructures. Microscopic solid-state phase transitions are highly affected by chemical as well as by mechanical driving forces, therefore the accurate calculation of chemo-mechanical configurational forces in the transition region is essential. In this work, we present a thermodynamically consistent and fully coupled multiphase-field model for chemo-mechanically driven phase transformation processes. A mechanical model based on the mechanical jump conditions on singular surfaces [Schneider et al. 2017] is coupled with a thermodynamically consistent multiphase-field approach for diffusive phase transformation processes [Choudhury and Nestler 2012]. This model enables the incorporation of CALPHAD-based parameters to render a quantitative chemical driving force. The configurational balance equation of capillarity with chemical and elastic driving forces, known as the generalized Gibbs-Thomson equation, together with the analytical solution of an ellipsoidal inclusion for the mechanical fields is considered to verify the thermodynamical consistency of our model. As applications, we show simulation results of the formation of Widmanstätten ferrite plates [Kubendran Amos et al. 2018] and discuss the influence of mechanical driving forces during the pearlitic phase transformation process.