Microstructure and texture evolution during hot rolling and subsequent annealing of Mg-1Gd alloy

The microstructure, texture and tensile ductility of Mg-1Gd alloy were investigated and compared to pure Mg following multipass rolling at 300 °C and isothermal annealing at 400 °C. The addition of Gd weakens the basal texture in both the as-rolled and annealed conditions, which is related to the enhanced activity of pyramidal 〈c+a〉-slip during hot rolling and the suppressed grain boundaries migration due to Gd segregation at grain boundary during annealing. A large number of secondary twins and shear bands formed during hot rolling of Mg-1Gd sheet may serve as favorable nucleation sites for static recrystallization during annealing. The recrystallized grains at bands/twins in Mg-1Gd alloy display a wide spread of orientations, which is similar to that in conventional Mg alloys. Pure Mg sheet shows a strong {0002} 〈11−20〉 texture component due to the preferred growth of grains with the 〈11−20〉 component during annealing. However, Gd solute segregation at grain boundary could inhibit the preferred growth of 〈11−20〉 grains, leading to a weak basal texture and a single 〈10−10〉 texture component in Mg-1Gd alloy sheet after annealing. The room-temperature ductility is significantly improved by the addition of Gd, which is mainly attributed to the texture weakening and grain refinement.