Microstructure and Tensile Strength Properties of Aluminium Alloys Composites Produced by Pressure-Assisted Aluminium Infiltration of Al2O3/SiC Preforms

Abstract

In this study, a process for the production of aluminium alloy metal– matrix composites (MMCs) by the liquid metal infiltration route was investigated. This process was based on Al2O3/SiC ceramic cake in different SiC that was obtained by chemical process rather than mixing of ceramic powders to obtain porous Al2O3/SiC ceramic foam. This product was heated up in ceramic crucible in the furnace. It was foamed by the effect of heat and as a result Al2O3/SiC ceramic cake was produced. Resulting Al2O3 grains had 3D honeycomb structure and SiC particles were in the alumina grains. Consequently, homogeneous powder mix and porosity were obtained within the cake. The morphology of the powder connections was networking with flaky particles. These flaky alumina particles provided huge amount of porosity, which was desired for ceramic preforms to allow liquid metal flow during infiltration. Resulting high porous ceramic cake (preform) was placed in a sealed die and liquid aluminium was infiltrated by Ar pressure. The obtained structure indicated that alumina and SiC particles were uniformly distributed with the Al-matrix. In addition, the flaky alumina particles were bonded chemically onto the surfaces during foaming process. The infiltration was achieved successfully; microstructure and tensile strength properties of the composites were examined.