Effects of Annealing Temperature on Phase Transformation Temperature and Friction and Wear Properties of Ti₅₀Ni₄₅Cu₅ Alloy

Ti50Ni45Cu5 (at.%) alloy ingot was prepared by smelting technique, and then a series of treatments were carried out as follows: homogenization and solid-solution treatment, cold rolling to reach 25% reduction and annealing at 400, 500, 600 and 700 ℃. The effects of annealing temperature on phase transformation temperature, mechanical properties and friction and wear properties of the alloy were studied. The results show that strength, hardness and martensite phase transformation temperatures of the alloy decreased while the plasticity increased with the increase of annealing temperature. Furthermore, the alloy annealed at 400 ℃ exhibited excellent comprehensive mechanical performances, and its tensile strength up to 996 MPa and elongation was 8.2%. The B2→B19′ transformation in Ti50Ni45Cu5 alloy had been found over a wide temperature range from -50 ℃ to +150 ℃. The wear mechanism of Ti50Ni45Cu5 alloy was spalling wear, and the wear-resistance decreased with the increase of annealing temperature. The alloy acquired good wear resistance due to the stress-induced martensite phase transformation. Moreover, the friction coefficient of the alloy annealed at 400 ℃ was 0.605 7 and wear mass loss was 0.007 4 g.