Strength and elastic modulus enhancement in Mg-Li-Al matrix composites reinforced by ex situ TiB₂ particles via stir casting

A novel Mg-10Li-3Al (wt.%, LA103) matrix composite reinforced by ex situ micron TiB₂ particles was developed in the present study. The ball milling and cold pressing pretreatment of the reinforcements made it feasible to prepare this material under stir casting conditions with good dispersion. The microstructure and mechanical properties of the composites prepared by different pretreatment methods were analyzed in detail. The TiB₂ particles in the Al-TiB₂/LA103 composite using the pretreatment process were uniformly distributed in the microstructure due to the formation of highly wettable core-shell units in the melt. Compared with the matrix alloys, the Al-TiB₂/LA103 composite exhibited effective strength and elastic modulus improvements while maintaining acceptable elongation. The strengthening effect in the composites was mainly attributed to the strong grain refining effect of TiB₂. This work shows a balance of high specific modulus (36.1 GPa·cm³·g^-1) and elongation (8.4%) with the conventional stir casting path, which is of considerable application value.