Size Model of Critical Temperature for Grain Growth in Nano V and Au

The intrinsic thermodynamical factors that dominate the stability of nanocrystallines are investigated through the microcosmic process of grain growth. The results suggest that nanocrystallines grows at a certain temperature and the critical temperature is determined by the vacancy formation energy and diffusion activation energy of the nanocrystallines. Based on the hypothesis, a simple model is proposed to predict the size-dependent critical temperature of grain growth. Within this model, we investigate the thermal stability of nanocrystallines V and Au, compared with the results available. It is shown that the critical temperature decreases with decreasing size, showing an evident size effect. The research reveals that the thermal stability is dependent on the energetic state of the nanocrystallines and the mobility of the inner atoms.