Grain growth kinetics and its effect on instrumented indentation response to nanocrystalline Ni

Thermal instability in nanocrystalline (nc) Ni with a grain size of ∼60 nm was studied in detail. The kinetics of thermal grain growth behavior was studied by DSC and resistivity experiments. Thermal instability was characterized 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 hardness and activation volume was investigated using nanoindentation technique. The interaction of dislocations-grain boundaries mediated mechanism was found to be the rate controlling plastic deformation mechanism.