The cyclic extrusion compression （CEC） was applied to severely deform the as-extruded GW102K （Mg- 10.0Gd-2.0Y-0.5Zr, wt%） alloy at 350, 400, and 450 ℃, respectively. The microstructure, texture, and grain boundary character distribution of the CECed alloy were investigated in the present work. The mechan- ical properties were measured by uniaxial tension at room temperature. The crack initiation on the longitudinal section near the tensile fracture-surface was investigated by high-resolution scanning elec- tron microscopy （SEM）. The result shows that the microstructure was dramatically refined by dynamic recrystallization （DRX）. The initial fiber texture was disintegrated and obviously weakened. The 8-passes/ 350 ℃ CECed alloy exhibited yield strength of 318 MPa with an elongation-to-fracture of 16.8%, increased by 41.3% and 162.5%, respectively. Moreover, the elongation-to-fracture of the 8-passes/450 ℃ CECed alloy significantly increased more than 3 times than that of the received alloy. The cracks were mainly initi- ated at twin boundaries and second phase/matrix interfaces during tensile deformation. The microstructure refinement was considered to result in the dramatically enhanced of the strength and ductility. In ad- dition, the texture randomization during CEC is beneficial for enhancing ductility. The standard positive Hall-Petch relationships have been obtained for the CECed GW102K alloy.
Jinbao LinXinyi WangWeijie RenXuexia YangQudong Wang
