Effects of cooling rate on the microstructure and properties of magnesium alloy-a review

Magnesium alloy is one of the most widely used lightweight structural materials, and the development of high strength-toughness magnesium alloy is an important research field at present and even in the future. The preparation process parameters of magnesium alloy directly affect the microstructure of the magnesium alloy, and then determine the properties of the magnesium alloy. The cooling rate has important effects on the microstructure and properties of the magnesium alloy, and is an important preparation process parameter that cannot be ignored. Both the cooling rate from liquid phase to solid phase and the cooling rate of the magnesium alloy after heat treatment will change the microstructure of the magnesium alloy. Furthermore, the properties of magnesium alloy will be affected. In this paper, the effects of cooling rate on the solidification behavior, the rheological behavior, the change of microstructure (the solid solution of alloying elements in matrix, the composition, size, distribution and morphology of second phase, the diffusion and segregation of alloying elements, the grain size, the formation and morphology of dendrite, etc.), and the effects of cooling rate of magnesium alloy after heat treatment on the microstructure and stress distribution are reviewed. The reasons for the divergence about the influence of cooling rate on the microstructure of magnesium alloy are analyzed in detail. The effects of cooling rate on the mechanical properties, corrosion resistance and oxidation resistance of magnesium alloy are also analyzed and discussed deeply. Finally, the new methods and approaches to study the effects of cooling rate on the microstructure and properties of magnesium alloy are prospected.