Plasticity of single-phase Ni-50Al intermetallics with large grains at high temperature

High temperature deformation behavior of single-phase Ni-50Al intermetallics with initial grain size of 220 μm was examined. It was found that the alloy exhibits plastic behavior under an initial strain rate of 7.5 × 10−4 s−1 to 1 × 10−3 s−1 in a temperature range of 1000-1100 °C. A maximum elongation of 139% was obtained under an initial strain rate of 8.75 × 10−4 s−1 at 1075 °C. The strain rate sensitivity, m value, is correlated with temperature and initial strain rate, being in the range of 0.16-0.263. Optical metallography (OM) showed that the grains were refined during plastic deformation from an initial size of 220 μm to less than 30 μm. Electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM) observations showed that an unstable subgrain boundary network formed during plastic deformation. The sub-grain boundaries were transformed into low and high angle grain boundaries by absorbing gliding dislocations. The large grained plastic phenomenon could be explained by continuous dynamic recovery and recrystallization (CDRR).