Microstructure, Texture, and Mechanical Properties of Mg-Gd-Y-Zr Alloy Prepared by Rotating Backward Extrusion Process

A cup-shaped Mg-Gd-Y-Zr alloy component has been successfully prepared by using the severe plastic deformation (SPD) technique of rotating backward extrusion (RBE), and the microstructure evolution and mechanical properties of different regions along the radial direction have been studied. In addition, the dynamic recrystallization (DRX) mechanism during the deformation process was further analyzed. The results indicate that the grain refinement effect significantly increased from the edge side to the inner side along the wall thickness direction. After RBE deformation, the average grain size of the sample decreased from similar to 106.01 mu m in the initial state to similar to 8.55 mu m in the innermost region of the cup wall. Many small and dispersed particle phases were distributed at the grain boundaries, and the DRX fraction reached 75.8%. Continuous dynamic recrystallization and discontinuous dynamic recrystallization occurred simultaneously. Due to the random orientation of the grains that underwent DRX, the texture intensity of the alloy was weakened. The microhardness and tensile properties of the alloy were tested along the wall thickness direction, and the fracture morphology was observed. The inner region exhibited the most excellent comprehensive mechanical properties, with yield strength, ultimate tensile strength, and elongation values of 323 MPa, 370 MPa, and 11.3%, respectively.