Modelling of grain refinement driven by negative grain boundary energy

AbstractGrain refinement can be described by the classical kinetic equation using a negative value of the specific grain boundary Gibbs energy. A respective overview is offered reporting according observations and simulations, particularly linked to grain boundary segregation. Classical grain growth model is used in the treatment of evolution of the distribution function during refinement. The adapted model requires defining nucleation rate of new grains, which significantly influences the kinetics of the system of grains. Moreover, a jump in the distribution function is allowed at a certain value of the grain radius RJ, which separates old grains from newly nucleated ones. Evolution equation for both the critical radius Rc and separation radius RJ (jump position) as well as for the dimension-free distribution (shape) function are derived. Illustrative examples for the evolution of the system parameters under various nucleation rates of newly generated grains are presented.