Microstructure and High-Temperature Mechanical Properties of Mg-1Al-12Y Alloy Containing LPSO Phase

Abstract

This paper describes our study on the effect of the long-period stacking order (LPSO) phase on the comprehensive mechanical properties of the as-cast Mg-1Al-12Y (wt. %) alloy. The microstructure and tensile mechanical properties of as-cast alloy and solution treatment alloy were evaluated. The results showed that α-Mg matrix, Al2Y phase and β-Mg24Y5 phase were present in the as-cast alloy. After solution treatment, the β-Mg24Y5 phase in the alloy was dissolved and the LPSO phase was precipitated. The solution treatment did not cause grain growth or Al2Y phase change, but the comprehensive mechanical properties of the alloy were significantly improved. This was mainly due to the precipitation of the LPSO phase in the solid solution alloy. In addition, the dissolution of the β-Mg24Y5 phase after solution treatment could also improve the mechanical properties. The improvement of the comprehensive mechanical properties of solution treatment alloys at room temperature was due to the dispersion strengthening caused by the intragranular LPSO phase dispersed within the alloy, which had a good blocking effect on the movement of dislocations. The ductility of the solid-solution alloy was greatly improved at a high temperature while maintaining high strength because the LPSO phase is kinked, the dislocation density was reduced, and more non-basal slip was activated during the high-temperature tension.