Effects of heating treatment and hot extrusion on microstructures and room temperature mechanical properties of Mg-10Gd-4.8Y-0.6Zr alloy

Microstructures and room temperature mechanical properties of Mg-10Gd-4.8Y-0.6Zr alloy in different treatment conditions were investigated by tensile test, energy dispersive spectrometer (EDS), X-ray diffraction(XRD), optical microscopy (OM), scanning electron microcopy (SEM), and transmission electron microscopy (TEM). The results show that the network-like eutectic compounds in cast alloy dissolve, and black cuboid-shaped phases form after homogenized at 520°C for 16 h. Both strength and plasticity of homogenized alloy increase obviously. The extrusion improves tensile strength by 25%, reaching 304.5 MPa, and yield strength increases in times, reaching 268.7 MPa. The peak hardness 137 HV can be obtained when aged at 200°C for 20 h. After extrusion and ageing, tensile strength reaches 370 MPa increasing by 22%, and yield strength reaches 295.6 MPa increasing by 10%. The fracture mode of Mg-10Gd-4.8Y-0.6Zr alloy at room temperature is a mixed fracture with both brittle fracture and ductile fracture.