Effect of Cold Working and Aging Treatments on Martensitic Transformation Characteristics and Shape Recovery Response in Ti ₅₀ Ni ₄₀ Cu ₁₀ Alloy

This study investigates the effects of 5%, 10%, and 15% cold rolling, followed by aging at 500°C and 600°C for 24 and 48 h, on the martensitic transformation, thermal hysteresis, and shape recovery ability of Ti 50 Ni 40 Cu 10 . The results from differential scanning calorimetry and X‐ray diffraction revealed that cold‐worked samples exhibited low martensitic transformation temperatures, which are below room temperature. This phenomenon is directly linked to the degree of cold working applied to the samples, resulting in the coexistence of both austenite and martensite phases in the material. The aging process increased the transformation temperatures to the 44°C–55°C range and modified hysteresis behavior. Aging at 500°C promoted the formation of disk‐like Cu‐rich (Ni, Cu) 3 Ti‐type precipitates, while aging at 600°C provided better conditions for recovery and recrystallization. The shape recovery feature of the samples is tested by conducting a stress–strain test at various maximum strains from 2% to 10%. The samples aged at 500°C for 24 h have the highest shape recovery. Longer aging at this temperature resulted in brittle samples, which fractured after 5% strain. Aging at 600°C is more beneficial for 48 h due to enhanced recovery and annihilation of dislocations.