Grain growth characteristics and its effect on deformation behavior in nanocrystalline Ni

Abstract

► The thermal grain growth behavior in nc-Ni was studied by DSC and resistivity experiments and activation energy for grain growth was determined. ► The effect of grain size on nanohardness and dynamic parameters like strain rate sensitivity and activation volume of nc-Ni was determined. ► The rate controlling plastic deformation mechanism was identified. The grain growth characteristics and its effect on deformation behavior of nanocrystalline(nc)-Ni having a grain size of 60 nm have been studied. The kinetics of thermal grain growth was studied by DSC and resistivity experiments. Thermal instability leading to grain growth in nc-Ni was assessed by determining the activation energy required for grain growth in the temperature range of 100–400 °C. The activation energy was found to be ∼100 kJ/mol below Curie temperature and ∼298 kJ/mol above Curie temperature. The effect of grain size on nano-hardness and loading rate was investigated using nanoindentation technique. The deformation parameters like strain rate sensitivity (m) and activation volume ( V * ) for different grain sizes in nc-Ni were also evaluated. The interaction of dislocations-grain boundaries mediated mechanism was appeared to be the rate controlling plastic deformation mechanism.