A thermodynamic framework for coupled multiphase Ginzburg-Landau/Cahn-Hilliard systems for simulation of lower bainitic transformation

摘要

A thermodynamic framework for a coupled Ginzburg-Landau/Cahn-Hilliard systems is presented in this work. It is based on the concept of generalized stresses and microforce balances as introduced by Gurtin (Phys D Nonlinear Phenom 92(3):178-192, 1996). His concept is extended to compute phase changes and diffusion simultaneously on the same domain and adding coupling terms between the quantities. The resulting thermodynamic framework distinguishes between basic balance laws which are universal and constitutive equations which depend on the specific material. As an application, the transformation of austenite to lower bainite is simulated in this work. The multiphase-field model describes the evolution of bainitic ferrite and the precipitation of carbides, while the Cahn-Hilliard equation governs the carbon diffusion within the bainitic ferrite.