Solidification processing of aluminum casting alloy reinforced with ceramic microspheres for thixoforming

Abstract

Cast aluminum matrix composites based on an Al-Si-Mg alloy have been developed. The reinforcement was in the form of hollow microspheres, a ceramic by-product from coal power stations. The particles were incorporated into the aluminum alloy melt by mechanical stirring either in the semisolid state or full liquid state. The composite melts were cast from full liquid temperature to produce slugs for thixoforming. The as-cast microstructure consisted of fine, equiaxed dendritic primary grains in a matrix of eutectic phases. The primary dendritic grains evolved to become non-dendritic after reheating the slugs to semisolid temperature. The slugs were subsequently thixoformed at a temperature cor..