Interfacial transition of Al-Si alloys in unidirectional solidification

Abstract

Interfacial transition (from smooth plane to cellular structure) of Al-Si alloys in unidirectional solidification was investigated. The transition occurred at
where C₀=1.6×10^-6G/R
C₀: Initial content of Si in molten aluminum
G: Temperature gradient in molten metal
R: Rate of solidification
It was assumed that isolated pits on the interface were the starting points of transition. It was observed that the change of the width of elongated cells was inversely proportional to the value of G^1/4×R^3/4 The shape of adhered layer on the decanted interface was often different from that of real interface.