Effects of remelting and refining on the microstructure and properties of particle reinforced magnesium-lithium matrix composites

Particle reinforced magnesium-lithium matrix composite ingot was remelted and refined using a special 100Kg level vacuum induction melting system. The evolution of microstructure, mechanical properties and homogeneity of ingot before and after remelting and refining was described and analyzed based on quantitative characterization. The refining mechanism was also explored. The results show that the secondary mechanical stir effect in the remelting process can purify the melt and reduce casting defects, significantly improve the distribution homogeneity and effectively reduce the aggregation of reinforcement particles. After the remelting and refining of YAl_2p/LA143 composite ingot, the homogeneity factor ζ_PD of reinforcement distribution increases by 22.8%, the area proportion of particle blocky aggregates decreases by 91.4%. The obvious atomic thermal diffusion effect between reinforcement phase and matrix phase was observed during the remelting and refining process. The element distribution of interface zone between reinforcement phase and matrix alloy phase shows a gentle curve transition after remelting and refining, which forms an excellent transition interface. Under the effects of secondary mechanical stir and atomic heat diffusion, the mechanical properties of YAl_2p/LA143 composite remelting ingot are effectively improved, and the tensile strength, yield strength and elongation increase by 11.3%, 10.2% and 400%, respectively.