Structure evolution mechanism and physical modeling of Ni60Ti40 during dynamic recrystallization

Abstract

The steady-state rheological stress, critical strain capacity, structure evolution dynamics, and energy dissipation during dynamic recrystallization of Ni60Ti40 alloy were characterized through single-pass isothermal compression experiments at 980–1070 °C and strain rate of 5 × 10−3 - 5 s−1. The underlying structural evolution mechanism was revealed via microstructure characterization. The critical strain capacity of Ni60Ti40 during dynamic recrystallization decreased and the structure transformation volume fraction increased with the rise of deformation temperature or the decline of strain rate. The critical power dissipation rate upon dynamic recrystallization was 0.15. At low temperature and high strain rate, the structure evolution was dominated by geometrical dynamic recrystallization. At high temperature and low strain rate, non-continuous dynamic recrystallization was dominant. The nucleation mechanism was grain boundary slip induced by dislocation motion.