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)

Grain refinement of metallic alloys is of critical importance to minimize the risk of solidification defects and obtain the desired mechanical properties. The effectiveness of grain refinement depends strongly on the interplay between potency of nucleant particles for heterogeneous nucleation and their ability for grain initiation. For a given alloy, the former is an inherent property of the nucleant particle while the latter is strongly dependant on the size, size distribution and spatial distribution of the nucleant particles. Through analytical and numerical modelling, it has been shown recently that agglomeration of the nucleant particles has a strong influence on their grain initiation behaviour, and is largely responsible for the discrepancy in grain size between theoretical predictions and experimental measurements. In this work, a cellular automaton model is used to investigate the effect of nucleant particle agglomeration on the effectiveness of grain refinement. The spatial distribution of nucleant particles is modelled by a log-normal distribution and the mean particle spacing is used to represent different levels of particle agglomeration. Other variables include alloy composition, particle size, size distribution and number density.