Research on the mechanical properties of Mg-5Gd-2Y-0.4Zr alloy manufactured by arc additive under direct aging treatment

The magnesium alloy with medium and low rare earth content, fabricated by wire and arc additive manufacturing（WAAM）, is expected to achieve excellent mechanical properties through direct aging treatment.The Mg-5Gd-2Y-0.4Zr alloy was fabricated by the WAAM, and its microstructure and mechanical properties under direct aging heat treatment were studied. The results indicate that the as-deposited alloy exhibits a fine grain size（≤26μm）, a high content of alloying elements in the matrix, and few intergranular second phases. After direct aging treated at 200℃ for 128h, the hardness of direct aging treated alloy increased from（63.3±2.2）HV_0.3 to（85.1±2.1）HV_0.3,reaching 95.6% of the hardness sf solution + aging treated alloy; while the tensile strength and yield strength increased from（217.3±2.8）MPa and（91.0±7.7）MPa to（240.3±1.6）MPa and（130.9±2.5）MPa, respectively.In conclusion, this study demonstrates that direct aging treatment has a remarkably strengthening effect on the mechanical properties of Mg-5Gd-2Y-0.4Zr alloy.