High temperature deformation and microstructural evolution of Mg-Gd-Y alloys

The high temperature deformation behaviours of Mg-10Gd-3Y (GW103) alloys processed by extrusion and extrusion followed by equal channel angular extrusion (ECAE) were investigated and compared, and the maximum tensile elongations of 390 and 490% were obtained in the two specimens respectively. The different processing routes led to different microstructural features, and the extrusion followed by ECAE (EX-ECAE) specimens usually showed higher elongations than as extruded ones under the same deformation conditions. The deformation mechanisms of GW103 alloys were analysed in terms of the strain rate sensitivity exponent, microstructural evolution and activation energy. The high elongations of as extruded specimens were attributed to the combined effects of dynamic recrystallisation and grain boundary sliding, which was accompanied by lattice diffusion. However, grain boundary sliding controlled by the combination of grain boundary and lattice diffusions was dominant in the EX-ECAE specimens.