Creep behavior and creep mechanism of Mg-Gd-Y-Sm-Zr alloy

Abstract

In this work, Mg-11Gd-2Y-3Sm-0.5Zr (GWS1123) alloy was arranged by vacuum melting and gas protection. The tensile mechanical properties at 20–300 °C and the creep properties at 200–300 °C/50–110 MPa were tested by tensile and creep testing machines, respectively. The microstructure changes were investigated by transmission electron microscopy before and after creep, and the strengthening mechanism and creep mechanism were discussed. In addition to its superior tensile strength at room and high temperatures, GWS1123 alloy exhibits excellent creep properties at high temperatures. At 250 °C, the ultimate tension strength and tensile yield strength are 319 MPa and 246 MPa, respectively, which are 26.6% and 22.4% higher than the ultimate tension strength (252 MPa) and tensile yield strength (201 MPa) at room temperature. The alloy has good creep resistance at 200–250 °C/50–110 MPa and 300 °C/50 MPa. The effect of creep temperature on the creep resistance is greater than that of stress. The creep mechanism of GWS1123 alloy at 200–300 °C/50–110 MPa is mainly grain boundary slip, dislocation slip and climb. It is the good heat resistance, strong Orowan strengthening effect and obvious coherent strengthening effect of β′ phase that are responsible for the high temperature strength and high temperature creep resistance.