Hot Deformation Behavior of TiNiCu Shape Memory Alloy

Compared with near equiatomic Ni-Ti alloys, Ti₅₀Ni_50-xCu_x shape memory alloys have small hysteresis of the phase transition temperature and super-elastic stress. When Cu content is less than 5 at.%, this small hysteresis phenomenon is no notability, while Cu content is more over 10 at.%, the alloys are brittle and prone to fracture during the hot deformation process. This paper investigated the hot deformation behavior and processes of TiNiCu alloy. The results show that the resistance to deformation of the alloy increases as the Cu content adds up and the deformation temperature and strain rate have an important impact. Especially, as temperature increase, the resistance to deformation remarkably decreases. Even Cu content is up to 10 at.%, the alloys have good deformation ability when deformed at appropriate temperature. The wrought process shows that Ti₅₀Ni₄₀Cu₁₀ alloy is prone to deformation and can be rolled into thin sheet. According to the Jonas hyperbolic sine model, the constitutive equations of the alloys have been established by regress the modified true stress-true strain curves. The calculation results obtained from the constitutive equation agree with the experimental results well.