Texture evolution in Mg-Zn-Ca alloy sheets

Ca was added to Mg-1Zn and Mg-6Zn alloys to modify their texture, and the origin of texture modification by Ca addition has been investigated. It shows that Mg-1Zn-1Ca (ZX11) and Mg-6Zn-1Ca (ZX61) alloy sheets in the as-rolled condition show the textures having a splitting of basal poles toward the rolling direction and a splitting of basal poles toward the transverse direction, respectively. An analysis of the micro structure in the as-rolled condition shows that two different types of twins become active during rolling, double twins for ZX11 and tension twins for ZX61, suggesting that double twinning and tension twinning promote a splitting of basal poles toward the rolling direction (ZX11) and transverse direction (ZX61), respectively. On the other hand, after annealing, both alloy sheets show a weakened texture characterized by a splitting of basal poles toward the transverse direction. During annealing, the growth of tension twin-oriented grains occurs, resulting in the texture having a splitting of basal poles toward the transverse direction in both alloys. These alloys show not only higher yield strength but also better stretch formability than Al 5052 alloy, showing their potential as highly formable Mg sheet alloys.