Triggering rare earth texture modification in magnesium alloys by addition of zinc and zirconium

Abstract

Two Mg alloys, Mg–1Zn–1Ce–0.6Zr and Mg–1Zn–1Gd–0.6Zr (wt.%), were subjected to large strain hot rolling treatment, followed by annealing at different temperatures. Nucleation of recrystallization initiated inside shear bands and in the vicinity of particles, resulting in a panorama of orientations with varying stored energies. Recrystallization resulted in the evolution of new, softer orientations, in terms of slip, accompanied by significant texture weakening. On comparison with their respective binary counterparts, the quaternaries established the significant role played by the additional presence of non-rare earth (non-RE) elements (Zn, Zr) in augmenting the RE texture modification effect. Contrary to Mg–1Ce, deformation/recrystallization texture modification in Mg–1Zn–0.6Zr–1Ce was governed by a complex interplay between precipitate redissolution and segregation events. Moreover, compared to Mg–1Gd, the Mg–1Zn–0.6Zr–1Gd alloy revealed deformation/recrystallization texture transition at lower annealing temperature. Such a behavior was attributed to an increased tendency of RE–non-RE solute-pairing/clustering in the latter, thereby amplifying solute drag and magnifying selective growth events. Tensile tests conducted post-annealing revealed remarkable ductility improvement in the quaternary alloys over their binary equivalents.