Hot deformation and dynamic recrystallization of NiTi intermetallic compound

• Published in: Journal of alloys and compounds 2014-11, Vol.614, p.56-59
• Main Authors: Mirzadeh, H., Parsa, M.H.
• Format: Article
• Language: English
• Subjects: Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: structure, mechanical and thermal properties; Constitutive relationships; Cross-disciplinary physics: materials science; rheology; Deformation; Deformation and plasticity (including yield, ductility, and superplasticity); Dynamic recrystallization; Exact sciences and technology; High-temperature deformation; Intermetallic compounds; Intermetallics; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Nickel base alloys; Nickel titanides; NiTi shape memory alloy; Physics; Power law; Shape memory alloys; Strain hardening rate; Stresses; Treatment of materials and its effects on microstructure and properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.06.063

•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 265kJ/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 50.5at.% Ni–49.5at.% Ti was studied using the hot compression flow curves corresponding to the temperature range of 700–1000°C under strain rate of 0.1s−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.