Non-equilibrium microstructure of hyper-eutectic Al-Si alloy solidified under superhigh pressure

The non-equilibrium microstructures of hyper-eutectic Al-26.6wt%Si solidifi ed under superhigh pressure (5.5 GPa) have been investigated. The results s how that there exists a great deal of primary alpha phase in hyper-eutectic Al-Si alloy. The non-equilibrium microstructure for hyper-eutectic Al-Si a lloy is composed of primary alpha phase, beta phase and (alpha + beta) eute ctic phase. The solid solubility of Si in alpha phase and the solid solubil ity of Al in beta phase increase significantly. The effects of high pressur e on the solidification structures of Al-Si alloy are discussed. (C) 1999 K luwer Academic Publishers.