Comparison between kinetic and thermodynamic effects on grain growth

A detailed comparison between the kinetic and the thermodynamic effects on grain growth was given, and the corresponding models were fitted to the experimental data, respectively. It was found that both models can explain the derivation from the normal parabolic growth under ideal condition. According to the kinetic model, a single isothermal grain growth can be understood in terms of a single, thermally-activated rate process with constant Q and grain boundary (GB) energy, σ_b; impurity atoms accumulated in the GBs might exert a retarding force on GB migration, but do not change the grain growth activation energy, Q. On the other hand, it is necessary to invoke variable Q and σ_b according to the thermodynamic model, where the probably existing impurities and/or surface oxide seem to block surface and/or GB diffusion path, thus increasing Q and reducing σ_b.