한국주조공학회

AC8A matrix composites reinforced with Ni-aluminide were fabricated by squeeze casting process, and the characteristics and nature of the growth of Ni-aluminide phases at the interface between nickel and aluminurn were investigated. In the as-cast composites, the reaction layer between Ni skeleton and aluminum matrix was found to be NiAl_3, regardless of the casting temperatures and the kinds of preforms. During high temperature solution treatment the NiAl_3 layer grew and formed new Ni_2Al_3 layer. Because of presence of the porosity formed by Kirkendall effect at the interface between NiAl_3 and aluminum matrix, the tensile strength of composites was inferior to that of AC8A matrix alloy. However, the composites exhibited superior wear resistance due to the formation Ni-aluminide intermetallic phases. Composite A, of which Ni skeleton was fully transformed into Ni-aluminide, shows better wear resistance than that of composite B which still possessed some unreacted Ni skeleton.