On the stability of rapid planar solidification during melt-substrate quenching

This paper investigates the validity of the assumption of planar interface in rapid solidification with the help of a linear stability analysis and a heat and mass diffusion model. An absolute stability criterion for the existence of planar interface is derived from linear stability theories. The criterion is based on a heat flux parameter that is determined from the heat and mass transfer considerations. The stability of the planar interface under given conditions is examined by comparing the model predicted interface velocity with the absolute stability velocity determined from the stability theories. Selected results are presented for an Al-2wt.%Cu alloy quenched on a copper substrate.