Nano-scale grain growth kinetics

An empirical relation among three important properties of grain boundary (GB), i.e. GB free energy, energy change of GB segregation, and GB excess, was shown. Accordingly, GB energy reduces with grain growth. Once GB energy is equal to zero, GBs will be in thermodynamic equilibrium in the presence of solute atoms and, therefore, grain growth stops with saturated GBs. Applying a kinetic model for nano-scale grain growth, some published experimental data were successfully reinterpreted. With progressing grain growth, the activation energy of grain growth increases, in contrast with the reduction of GB energy. In connection with a semi-empirical relation according to the conjecture that GB energy is the difference between those responsible for diffusion in the lattice and the GB itself, proposed by Borisov, a conclusion can be drawn that, for alloy with strong segregation tendency, grain growth is inhibited due to the reduction of GB energy, even to zero.