Effect of Cu on Amorphization of a TiNi Alloy during HPT and Shape Memory Effect after Post‐Deformation Annealing

A ternary TiNiCu memory alloy was subjected to high‐pressure torsion (HPT) followed by post‐deformation annealing (PDA) to study the effect of Cu (5 at%) on amorphization after HPT processing and also the microstructural evolution and shape memory effect (SME) after PDA. The results show that even after 20 revolutions the ternary alloy contains nanocrystalline areas and the microstructure is not fully amorphous. An easier martensite to austenite transformation and minor remaining austenite in the ternary alloy are responsible for suppressing amorphization. PDA at 673 K provides nanocrystalline microstructures containing an R‐phase with a minor martensitic B19' phase in the ternary alloy. The SME of this alloy after PDA is not as satisfactory as for the binary alloy processed through similar conditions because of the existence of a high volume fraction of the R‐phase. Nevertheless, the total recovered strain of the ternary alloy after PDA for 30 min has a maximum value of 6.5%.