Texture Formation through Thermomechanical Treatment and Its Effect on Superelasticity in Mg-Sc Shape Memory Alloy

The formation of texture through thermomechanical treatment was investigated in Mg-18.8 at% Sc shape memory alloy to enhance its superelasticity at room temperature. The samples were cold rolled in an alpha phase or in a beta phase and then finally heat treated at 690 degrees C followed by water quenching to obtain a beta phase. In the case of cold rolling in the alpha phase, a basal-plane texture was formed, while no preferential texture was observed along in-plane direction. After the final heat treatment, {011} < uvw >(beta) transformation texture was obtained, according to Burgers relationship, indicating no improvement of the superelasticity along in-plane direction. In the case of the cold rolling in the beta phase, a weak {111}< 011 >(beta) recrystallization texture was obtained. The sample showed about 0.65% superelastic tensile strain along rolling direction, while that along transverse direction (//similar to < 113 >beta) showed only about 0.43%. This trend is in good agreement with the orientation dependence of the transformation strain, but, the obtained superelastic strain was much lower than the expected value, which is due to the weak texture and suggests the existence of a strong grain constraint in the Mg-Sc shape memory alloy.