Magnesium alloy microstructure is one of the key factors determining the mechanical properties of the later stage. Due to the complexity of the hexagonal structure (hcp) of magnesium alloys, the traditional microscopic characterization methods can not fully satisfy the tracking of the microstructure and evolution of magnesium alloys. With the development of numerical simulation technology, phase field simulation technology has gradually become a powerful tool for simulating the microstructure evolution of magnesium alloy with its unique advantages. The close-packed hexagonal structure has an anisotropic feature different from the face-centered cubic crystal (fcc), and a phase field model suitable for the hcp structure needs to be established. At present, many of the phase field simulations are mostly concentrated on the alloy of the cubic structural system, and the phase field simulation of the alloy of hcp structure is relatively late. In particular, magnesium alloy, as the lightest metal structural material, has the advantages of low density, high specific strength and high specific stiffness, and is widely used in aviation, automobile and defense military industries. Although a large number of phase field simulation studies on the microstructure evolution of magnesium alloys have been carried out in recent years, many problems still face: (i) most of the research is concentrated on the simulation of commercial magnesium alloys, while the simulation studies of other magnesium-based alloys such as magnesium rare earth alloys are relatively comparative; (ii) the simulation scales are mostly two-dimensional, and the simulation results of three-dimensional and four-dimensional scales are relatively few; (iii) the simulation work of magnesium alloy microstructure under the physical field, ultrasonic field, magnetic field and other physical fields is relatively small. In recent years, based on phase-field simulation, different factors such as external field are taken into account in the simulation process, which makes the two-dimensional and three-dimensional simulation of magnesium alloy in the field of dendrite evolution, grain growth and precipitation phase precipitation more realistic. The KKS model and multiphase field model based on the phase field model and thermophysical parameters were first applied in the solidification process of magnesium alloy, and the simulation results similar to the experiment were obtained. The simulation of the microstructure of the alloy was quickly advanced, but the multiphase field The simulation results of the model and the KKS model are mostly qualitative descriptions, and it is difficult to achieve quantitative comparison. The combination of Karma quantitative model and anisotropic parameters effectively solves the quantitative problem of phase field simulation. Subsequently, the phase field simulation applied to the recrystallization of magnesium alloys, recurring the microscopic evolution of recrystallization nucleation and grain growth at different annealing temperatures, and revealed the dynamic mechanism of recrystallization nucleation and growth. The phase field simulation of solid-state phase transition of magnesium alloy started relatively late. The interaction between interface energy and elastic strain energy needs to be considered in the simulation process. The precipitated phase presents a diamond-shaped or lath-like morphology similar to the experimental results. Based on the introduction of phase field method, this paper first introduces the application and development of phase field simulation technology in solidification microstructure of magnesium alloy, and discusses the experimental results of phase field simulation technology in the microstructure solidification microstructure of magnesium alloy, followed by recrystallization of magnesium alloy. The phase field simulation study of grain growth is described. The development history of phase field simulation in magnesium alloy solid phase transformation process is also reviewed. Finally, the paper points out the main problems of phase field simulation in the microstructure evolution of magnesium alloy, and looks forward to the development trend and future prospects of this field. © 2019, Materials Review Magazine. All right reserved.
