Structure stability and mechanical properties of high-pressure die-cast Mg-Al-La-Y-based alloy

Mg-3.0Al-2.2La-0.3Y-0.2Mn (wt.%) alloy was prepared by high-pressure die-casting. The microstructure, thermal stability of intermetallic phases and mechanical properties were investigated. The dominant strengthening phase is Al₁₁La₃, mainly distributed in the interdendritic regions. The Al₁₁La₃ phase exhibits good thermal stability with no significant decomposition at temperatures up to 200°C within 800h, while almost all Al₁₁La₃ intermetallics decompose to Al₂La at higher temperature of 450°C for 800h. The alloy exhibits significantly improved tensile and compressive yield strengths at room temperature and 200°C. The outstanding mechanical properties are mainly attributed to the formation of Al₁₁La₃ intermetallics, which is present in a high volume fraction, and possesses fine morphology and relatively good thermal stability.