Microstructure and mechanical properties of SiC reinforced AIN/AI composites

Abstract

Interconnected network of AIN/AI composites are produced by in situ liquid metal-gas reactions. In this study, various Al-Si-Mg alloys are nitrided in N2-4%H2 atmosphere to understand the composite growth mechanism. Both fibre and particulate SiC reinforcements are infiltrated with AIN/AI reaction product to form near dense composites and mechanical properties are compared with those of AIN paniculate reinforced AIN/AI composite. The composite microstructure is found to be sensitive to the processing temperature, alloy composition and filler material size and chemistry. The variation in mechanical property is also dependent on the residual porosity. Formation of moisture sensitive Al4C3 in SiC reinforced composites causes deterioration of mechanical properties. Various alternatives to prevent Al4C3 formation are discussed in the text.