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 800 h, while almost all Al11La3 intermetallics decompose to Al2La at higher temperature of 450 °C for 800 h. 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.

► A new heat-resistant Mg–Al–La–Y-based alloy was designed and prepared by high-pressure die-cast technique.
► Fine microstructure with main strengthening phase Al11La3 was obtained.
► The clear evidence of Al11La3 phase transition was obtained.
► The improved mechanical properties of HPDC Mg–3.0Al–2.2La–0.3Y–0.2Mn (wt.%) alloy were obtained.