Cold-rolling and Recovery Behaviours of Ti₃Al Single Crystals with DO₁₉ Structure

Abstract

Effects of activated slip systems, rolling direction and chemical composition on cold-rolling behaviours were investigated in Ti₃Al single crystals containing 25.0 at% Al and 33.0 at% Al with the DO₁₉ structure. Work-hardening and deformability of Ti₃Al depended strongly on the operative slip systems. When the rolling axis and rolling plane was controlled to operate dominantly prism slip of {1010}<1210>, Ti-25.0 at%Al single crystals could be cold-rolled to about 60% reduction in thickness accompanied by gradual work hardening. However, activation of slips on (0001) and {1121} pyramidal planes induced strong work-hardening resulting in poor ductility. Deformability of Ti₃Al was influenced by chemical composition and the best deformability was obtained at the stoichiometric composition. Annealing after heavy cold-rolling resulted in the occurrence of polygonisation. A Ti₃Al sheet was obtained by a thermo-mechanical process combining cold-rolling with annealing.