High-temperature shape memory effect in Ti₅₀Pd_{50 - x}Ni_x (x = 10, 15, 20) alloys

High-temperature tensile tests on Ti₅₀Pd_{50 - x}Ni_x (x = 10, 15, 20) alloys were carried out at 293-858 K. The alloys were cold rolled with a 24.2-26.4% reduction in thickness and then heat treated for solution or recovery treatment. Shape recovery as well as the critical stress for reorientation of martensite variants and/or detwinning were measured as a function of alloy's composition and type of heat treatment. It was found that the critical stress was strongly affected by: (1) Ni content, (2) phase state (martensitic or austenitic) in which recovery treatment was performed. Finally, the key factor for improving shape memory characteristics by thermomechanical treatment in this metallic system was established and the shape memory characteristics of Ti₅₀Pd₄₀Ni₁₀ were improved remarkably by flash heating followed by a recovery heat treatment.