Phase field modeling of discontinuous dynamic recrystallization in hot deformation of magnesium alloys

A phase field model of discontinuous dynamic recrystallization (PF-DDRX) was employed to investigate grain structure evolution and its impact on mechanical response during thermo-mechanical processing of magnesium alloys. A set of isothermal compression experiments were conducted by thermo-mechanical simulator and used to calibrate the PF-DDRX model parameters such as the critical stress of recrystallization, the activation energy coefficient of dislocation, grain boundary mobility and recrystallization grain nucleation. The grain structure features of poly-crystalline magnesium alloys were used to generate the initial grain structure for DDRX simulations. Simulation results show that 1) the 'necklace' microstructures, which are often observed in DDRX, form at the earlier stage of recrystallization; and 2) both predicted grain structure and mechanical response are in a reasonable agreement with experimental data. More importantly, the results demonstrate that the proposed methods enable one to establish the relationships between PF-DDRX model parameters and material properties for quantitative prediction and design of grain microstructures and material properties with thermomechanical processes.