Superelasticity and Shape Memory Behaviors of Ti-25 at. Nb Alloy Processed by ECAP and Aging

摘要

Microstructure and mechanical behavior of Ti-25at.% Nb shape memory alloy processed by equal-channel angular pressing (ECAP) at 823K have been investigated. The effect of multi-passes ECAP and aging on the martensitic transformation temperature, shape memory effect and superelastic recovery strains of Ti-25at.%Nb alloy have been analyzed. It is found that with the increase of the pass number of ECAP, the yield stress decreases gradually, but the strain hardening rate increase obviously. After one pass ECAP and 573K aging treatment, a perfect superelasticity is obtained when the tensile strain is no more than 2%. Aging at 573K for 1 hour after ECAP, the yield stress and flow stress increase sharply, the shape memory effect and superelasticity change little.