Hot deformation and dynamic recrystallization of NiTi intermetallic compound

• Hot deformation behavior and dynamic recrystallization (DRX) in NiTi alloy.
• The normalized critical stress and strain for initiation of DRX of 0.98 and 0.72.
• The hot deformation activation energy of 265 kJ/mol for calculation of Z.
• A power law constitutive equation for the peak stress with a Z exponent of 0.15.

The hot deformation behavior of a binary nitinol alloy with chemical composition of 50.5 at.% Ni–49.5 at.% Ti was studied using the hot compression flow curves corresponding to the temperature range of 700–1000 °C under strain rate of 0.1 s−1. The typical single-peak dynamic recrystallization (DRX) behavior was seen in the resultant flow curves. The strain hardening rate analysis was used to reveal if DRX occurred. The effect of the Zener–Hollomon parameter (Z) on the characteristic points of flow curves was studied using the power law relations. The normalized critical stress and strain for initiation of DRX were respectively found to be 0.98 and 0.73. A power law constitutive equation, which relates the peak stress to Z with a Z exponent of 0.15, was proposed to characterize the hot working response of the investigated material.

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