Deformation mechanism, orientation evolution and mechanical properties of annealed cross-rolled Mg-Zn-Zr-Y-Gd sheet during tension

Mg-6.75Zn-0.57Zr-0.4Y-0.18Gd (wt.%) sheet with typical basal texture was produced by cross rolling and annealing. Room temperature tensile tests were subsequently conducted along rolling direction (RD), transverse direction (TD), and diagonal direction (RD45). Deformation mechanism and orientation evolution during the tension were investigated by quasi-in-situ electron backscatter diffraction observation and in-grain misorientation axis analysis. The results indicate that the activation of deformation mechanism mainly depends on the initial grain orientation. For RD sample, prismatic 〈a〉 slip plays an important role in the deformation of grains with 〈0001〉 axis nearly perpendicular to the RD. With the 〈0001〉 axis gradually tilted towards the RD, basal 〈a〉 slip becomes the dominant deformation mode. After the tensile fracture, the initial concentrically distributed {0001} pole is split into double peaks extending perpendicular to the RD, and the randomly distributed {101¯0} pole becomes parallel to the RD. The evolution in {0001} and {101¯0} poles during tension is related to the lattice rotation induced by basal 〈a〉 slip and prismatic 〈a〉 slip, respectively. TD and RD45 samples exhibit similar deformation mechanism and orientation evolution as the RD sample, which results in the nearly isotropic mechanical properties in the annealed cross-rolled sheet.