The effect of temperature on the grain growth of nanocrystalline metals and its simulation by molecular dynamics method

In this study, the thermodynamic stability of the grain boundaries and the grain growth of nanocrystalline Palladium (Pd) at various temperatures were investigated. For this purpose, the Gibbs free energy curves of grain boundaries were plotted in terms of the excess volume by the use of the equation of state (EOS) and Song’s thermodynamic models. The results showed that, according to the prediction of these models, the nanocrystalline growth in metals was stopped at the grain sizes less than the critical grain size. Also, the results of the temperature variations and its effect on the Gibbs free energy curves showed that by the increase of the temperature, the possibility for the stoppage of grain growth is facilitated and the critical grain size is increased. To investigate the validity of the mentioned predictions, the molecular dynamics atomic simulation was employed. The results obtained from the simulation, confirmed the predicted effect of temperature on grain growth of nanocrystalline Pd and showed that the EOS model is more accurate for the prediction of grain growth than Song’s model.