Hot deformation characteristics and dynamic recrystallization of the MoNbHfZrTi refractory high-entropy alloy

The hot deformation characteristics of dynamic recrystallization (DRX) of the MoNbHfZrTi refractory high-entropy alloy (HEA) was investigated using the isothermal compression tests in the strain rate of 0.001-0.1 s−1 at the temperature range of 800-1200 °C. Scanning electron microscope (SEM) with the electron backscatter diffraction (EBSD) technique was used to study the effect of deformation temperature and strain rate on the stress-strain behavior, microstructure evolution and dynamic recrystallization (DRX) during hot deformation. At 800 °C, the stress-strain curve exhibits a work-hardening stage until fracture at the strain rate of 0.1 s−1 and 0.01 s−1. Under other deformation conditions, the stress-strain curves exhibit the typical DRX characteristics. On the whole, the stress decreases with the increase of deformation temperature and decrease of the strain rate. The initial dendritic structure gradually disappears and more dynamic recrystallized grains form with the decrease of strain rate and the increase of the deformation temperature. The nucleation mechanism of discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) occurred simultaneously for the MoNbHfZrTi alloy during hot deformation. The effect of CDRX was weakened with the increase of deformation temperature and with the decrease of strain rate.