The flowability of particulate TiB2-containing metal matrix composite

This paper reports a study of the flow behaviour of a particulate TiB2-containing metal matrix composite (MMC) and a SiC particulate MMC containing the same matrix alloy, both in comparison with the unreinforced matrix alloy, Al-7Si-0.4Mg.Both the MMCs exhibited a similar extreme sensitivity to surface turbulence during casting, to the point at which it was not easily possible to produce good-quality castings using a conventional gravity-poured filling system. Further results obtained from fluidity measurements showed that the fluidity is not so different to conventional casting alloys, although the fluidity of the TiB2 MMC was slightly less good than the Al-SiC metal matrix composite, which in turn was poorer than the matrix alloy. A surprising result was that increasing the casting temperature did not significantly improve the fluidity of either of the MMCs.The relatively low fluidity and the high density of major defects appears to be associated with the high viscosity of the mixture and the fact that ...