High Pressure Squeeze Casting of Unidirectional Graphite Fiber Reinforced Aluminum Matrix Composites

Abstract

High pressure squeeze casting has been developed to fabricate unidirec tional fiber reinforced metal matrix composites having a wide range of fiber volume frac tion. The process development required innovative die-design in order to minimize the direct contact of molten metal with the metallic die, to prevent liquid metal escape from the die, to ensure fast infiltration and rapid solidification under high pressure. However, the application of high pressure causes certain difficulties, such as maintaining all fibers aligned in one direction and ensuring their uniform distribution in any cross section of the composites. This paper addresses the techniques used to overcome these difficulties. Tensile test results for graphite fiber reinforced aluminum matrix composites are pre sented and discussed. Optical and scanning electron microscopy analysis of polished and fracture surfaces provide details of fiber/matrix interface characteristics and fracture mechanisms of the composites.