Evolution of Microstructure, Texture, and Room Temperature Mechanical Properties of Hot-Extruded Mg-4Gd-xZn Alloys with Homogenization Followed by Furnace Cooling Treatment

Microstructure, texture and room temperature mechanical properties of hot-extruded Mg-4Gd-xZn (0, 1, 2 wt%) alloys were comparatively investigated. The results showed that hot-extruded Mg-4Gd-xZn alloys was mainly consist of α-Mg matrix and second phases streamlined along extrusion direction. Besides, some LPSO/SFs and W phases were found in grain interiors of hot-extruded Mg-4Gd-(1, 2) Zn alloys. With the increase of Zn content, the average grain size was firstly refined from 18.5 to 7.5 μm and then increased to 9.3 μm. The proportion of rare earth texture component of hot-extruded Mg-4Gd alloy was decreased after Zn addition, with the lowest proportion observed in the hot-extruded Mg-4Gd-1Zn alloy. It was found that hot-extruded Mg-4Gd-1Zn alloy exhibited the best room temperature mechanical properties, with yield strength, ultimate tensile strength and elongation of 150 MPa, 244 MPa and 29.3%, respectively. Compared with the hot-extruded Mg-4Gd alloy, its yield strength was improved by 58 MPa, with grain boundary and texture strengthening providing the strength increment of over 60%.