Modelling of kinetics of solidification of intermetallic compounds

Rapid solidification of an intermetallic compound can be associated with a reduction in the chemical long-range order in the solid at the solid/liquid interface. This reduced degree of order can result in unique kinetic effects such as marked interfacial undercoolings, anomalous partitioning behaviour and disorder trapping. The kinetic effects can be predicted by modelling of solidification kinetics incorporating variations of order parameter. This work presents an example of such modelling. The predictions are in the form of relations between explicit processing variables (such as melt composition and undercooling) and growth rate; thus, they can be tested against experiments concerning direct kinetic measurements. This is done by modelling of dendritic growth into an undercooled melt, taking account of displacements of the phase boundaries due to non-equilibrium effects. In contrast to the conventional analysis of the dendritic growth in intermetallics, growth of both the ordered and the disordered versions of the solid is treated in a single kinetic model and disorder trapping transitions are not excluded from the predictions.