ON THE STABILITY OF RAPID PLANAR SOLIDIFICATION DURING MELT-SUBSTRATEQUENCHING

This paper investigates the validity of the assumption of planar inter face in rapid solidification with the help of a linear stability analy sis and a heat and mass diffusion model. An absolute stability criteri on for the existence of planar interface is derived from linear stabil ity theories. The criterion is based on a heat flux parameter that is determined from the heat and mass transfer considerations. The stabili ty of the planar interface under given conditions is examined by compa ring the model predicted interface velocity with the absolute stabilit y velocity determined from the stability theories. Selected results ar e presented for an Al-2wt.%Cu alloy quenched on a copper substrate. (C ) 1997 Elsevier Science S.A.