Microstructure Evolution of the Mg-3Zn-0.5Er Alloy during Hot Rolling

Abstract

The microstructure evolution of the as-rolled Mg-3Zn-0.5Er alloy (wt.%) has been investigated. The results showed that the phase constituents of the sheet were composed of the α-Mg solid solution and the I-phase (Icosahedral quasicrystalline). The microstructure of sheets transformed from the deformation twinning into dynamic recrystallization (DRX) grains. Furthermore, the deformation twinning appeared again in the dynamic recrystallization grains during further hot rolling. It indicated that the twining was the main deformation mechanism and marginal dynamic recrystallization (DRX) occurred in the deformation twins at low strains. As the reduction reached 39.6%, the twin dynamic recrystallization (TDRX) regions cluster and widen by consumption of the initial deformation twins, then formed shear bands. After the reduction exceeded 66.3%, the microstructures of sheets were composed of equiaxed DRXed grains and fine twins. Moreover, compared with the RD-ND plane, the RD-TD plane had a smaller average grain size, ultimately reached ~15.8μm, which also led to a higher average value of the hardness.