Effect of casting techniques on tensile properties of cast aluminium alloy (Al-Si-Mg) and TiB2 containing metal matrix composite

An analysis of the statistical distribution of the tensile strength of a TiB2 containing aluminium matrix composite and its matrix alloy (Al -7Si-0(.)35Mg) was carried out using different casting techniques. The scatter of the tensile strength data was assessed by Weibull statistics. Results for the metal matrix composite (MMC) and the matrix alloy in as cast and heat treated conditions were compared. It was found that a low turbulence casting technique resulted in less scatter of tensile values, confirming the greater reliability of the cast material. Fractographic examination of the fractured faces of lower strength specimens showed that entrained oxide films play an important role in failure of the specimens. Heat treatment causes increased scatter in strength values, reflected in the lower Weibull modulus.