Y and Sm Synergistically Enhance the Microstructure and Mechanical Properties of Extruded Mg–7Al–1Ca Magnesium Alloy

Mg–Al–Ca series alloys have attracted significant research and development interest worldwide due to their high potential as magnesium alloys. However, their performance has yet to meet the anticipated targets. Alloying and plastic deformation are effective strategies for enhancing the overall properties of magnesium alloys. In this study, rare earth elements Y and Sm were added in equal proportion (Y:Sm = 2:1) to a Mg–7Al–1Ca alloy, followed by hot extrusion. The results show that the addition of Y and Sm effectively refined the grain size of the alloy. After extrusion, the Mg–7Al–1Ca–0.7Y–0.35Sm alloy exhibited the finest grains, with an average size of 13.16 μm. Furthermore, Y and Sm react with Al to form Al ₂ Y and Al ₂ Sm phases, which possess superior thermal stability. This process suppresses the formation of the β‐Mg ₁₇ Al ₁₂ phase. The Mg–7Al–1Ca–0.7Y–0.35Sm alloy also displayed a high recrystallization ratio of 81.6%, an increased average local misorientation angle, and a higher Schmid factor on the prismatic plane. The alloy exhibited a typical basal texture. The study concludes that the Mg–7Al–1Ca–0.7Y–0.35Sm alloy demonstrates the best combination of mechanical properties, achieving a tensile strength of 285 MPa, an elongation of 8.3%, and a hardness of 78.03 HV.