THE PROCESSING AND CHARACTERIZATION OF SINTERED METAL-REINFORCED ALUMINUM-MATRIX COMPOSITES

The current investigation involves the fabrication and characterizatio n of an aluminium metal matrix composite reinforced with sintered meta l preforms. Two types of metallic preforms were used (steel and stainl ess steel) and a variety of squeeze casting conditions were investigat ed using systematic design-of-experiments techniques to determine the effect of casting conditions on the composite microstructure and mecha nical properties. It was observed that a detrimental reaction phase co ntaining iron, aluminium and silicon formed around the metallic prefor m particles, with a lower volume fraction of reaction phase forming at the lower melt casting temperature. This reaction phase appears to pr omote premature fracture by facilitating crack initiation and propagat ion. The stainless steel-reinforced composites had a smaller volume fr action of reaction phase and exhibited superior properties compared to the steel-reinforced composites.