5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

Effective grain refinement strongly depends on the interplay between nucleation potency of nucleant particles (measured by nucleation undercooling), grain initiation behaviour (affected by size, size distribution, spatial distribution and number density of nucleant particles) and solidification conditions (specified by alloy concentrations and cooling rate). Recently, we have made good progress in understanding grain initiation behaviour, and developed the concepts of progressive grain initiation and explosive grain initiation. We found that the most effective grain refinement can be achieved by impeding nucleation using nucleant particles of least potency, which is in direct contrast to the traditional approach to grain refinement, in which the most potent nucleant particles are used to enhance heterogeneous nucleation. In this contribution we present our latest understanding of effective grain refinement though analytical and numerical modelling of solidification processes. We will show that grain initiation behaviour can be best represented by a grain initiation map, which can be used as a practical guide for effective grain refinement.