Formation of metastable crystalline phases in light-metal systems by rapid solidification

Abstract

Abstract The experimental facts concerning the formation of extended terminal solid solutions and new crystalline intermediate phases as a result of rapid solidification of Al and Mg alloys are reviewed and the available approaches to systematization and interpretation of such results are discussed. It is argued that, while alloy chemical and thermodynamic approaches are useful for identifying alloy systems that may be susceptible to particular non-equilibrium effects, kinetic modelling is required to predict the outcome of particular conditions of rapid solidification. The recent progress in such modelling and prediction of morphology, composition, growth temperature and microstructural spacing of solid phases generated by rapid solidification at known front velocity is assessed. To conclude, the practical significance of this emerging capability to predict the consequences of rapid solidification, as applied to light alloys, is outlined.