Hot Deformation Behavior of NiTiHf Shape Memory Alloy Under Hot Compression Test

In the present work, the hot deformation behavior of Ni₄₉Ti₃₆Hf₁₅ alloy was investigated. The compression tests carried out at the temperatures ranging from 800 to 1100 ◦C and at the strain rates of 0.001–1 s⁻¹. The peak stress decrease with increasing deformation temperature and decreasing strain rate, which can be represented by the Zener–Hollomon parameter. It was realized that dynamic recrystallization (DRX) was responsible for flow softening. All of samples exhibited typical DRX stress-strain curves with a single peak stress followed by a gradual fall down stress. The hyperbolic-sine-type constitutive model of Ni₄₉Ti₃₆Hf₁₅ alloy was obtained to provide basic data for determining reasonable forming process. The activation energy regarding the hot deformation of Ni49Ti36Hf15 was about 410.25 KJ/mol.