Anneal hardening of a nanostructured Cu-Al alloy processed by high-pressure torsion and rolling

A Cu-7 wt% Al alloy was processed by high-pressure torsion and rolling to obtain nanostructure and then annealed at a series of different temperatures. Annealing at 250 °C for 120 min produced higher strength, which is attributed to the formation of nanoscale annealing twins. It is proposed that the high densities of stacking faults and nonequilibrium grain boundaries, combined with the high residual shear stresses in the deformed samples, contribute to the development of nanoscale annealing twins during the recrystallization process.