Solute segregation in an Al_2O_(3f)/Al-4.5Cu alloy composite during solidification at different cooling rates

摘要

An Al_2O_(3f)/Al-4.5Cu composite was made by squeeze casting. The solute segregation in the composite at different cooling rates was studied. The results indicate that the primary crystal of Al-4.5Cu alloy nucleates and grows in the interstice between fibers. The fiber surface cannot serve as site for the heterogeneous nucleation of a primary dendrite. There exists an increasing Cu concentration gradient from the center of the interstice between fibers to the interface or the grain boundaries. There are the eutectic phases around the fibers. The solute segregation in the matrix increases with the cooling rate rising. The amount of eutectic phases followed by imbalance crystalline can be numerically calculated with Clyne-Kurz formula.