The development of predictive models for rapid surface melting and resolidification requires coupling of realistic heat flow models to emerging theories of rapid solidification processing. Attainment of unique microstructures and phases,for example through plane-front solidification and solute trapping, can be correlated to solid/liquid interface velocity,temperature and temperature gradients, and to theories of morphological stability. However, there are important limitations on achievable solid/liquid interface velocity depending upon the heating mode and heat flux distribution,melt thickness and location of the interface within the molten zone.
An overview is given of the emerging guidelines for prediction and control of rapid solidification conditions and microstructures. Homogenization of the liquid by convection and diffusion is also discussed. Electron beam surface melting of alloy substrates is used as an example of these processes.