Effects of Heat Treatment on Microstructure and Mechanical Properties of as-Extruded Mg-9Sn-1.5Y-0.4Zr Magnesium Alloy

The effects of heat treatment on microstructure and mechanical properties of the as-extruded Mg-9Sn-1.5Y-0.4Zr (wt%) alloy were investigated experimentally. The results show that the heat treatment plays an important role on the microstructure and mechanical properties of the as-extruded Mg-9Sn-1.5Y-0.4Zr alloy. The as-extruded alloy is mainly composed of non-uniform Mg2Sn phase. After the solution treatment at 495 °C for 10 h, a majority of Mg2Sn phases in the alloy dissolve into the matrix. Aging treatment can highly improve the mechanical properties of the Mg-9Sn-1.5Y-0.4Zr alloy. The optimized experimental condition is aging at 250 °C for 60 h after solution treatment at 495 °C for 10 h. The corresponding mechanical property parameters are: hardness HV of 890 MPa, ultimate tensile strength of 262 MPa, yield strength of 218 MPa, and elongation of 10.4%. Based on the experimental analysis, we find that the precipitation strengthening is the main contributor (∼51.76%) to the total yield strength in the aged experimental alloy.