ALTERNATIVES TO THE AL-SI EUTECTIC SYSTEM IN ALUMINUM CASTING ALLOYS

Many of the aluminum casting alloys used today are based on the aluminum-silicon eutectic system, because it imparts excellent casting ability to the alloys. However, the high temperature strength of these alloys is limited. Therefore, it is desirable to find alternate eutectic systems that would become the basis for a new generation of aluminum casting alloys that possess higher strength at room and elevated temperatures. In this study, the aluminum-nickel, aluminum-iron and aluminum-iron-nickel eutectic systems are presented as potential alternatives to the aluminum-silicon eutectic system for constituting aluminum casting alloys. The casting ability and tensile properties at room and elevated [350 degrees C (662 degrees F)] temperatures were measured and compared to those of the aluminum-silicon eutectic. The casting ability and room temperature tensile properties of the alternative eutectics were found to be competitive with those of the aluminum-silicon eutectic, while the alternative eutectic systems have a significant advantage in elevated temperature tensile strength.