Microstructure and properties of bilayer-graded Al-matrix composites by one-step pressureless infiltration of B 4 C/rice-husk ash preforms

The quantitative effect of the following parameters on the one single step pressureless infiltration characteristics of bilayer B 4 C p /rice-husk ash (RHA) porous preforms by aluminum alloys was investigated using the Taguchi method and analysis of variance (ANOVA): infiltration temperature and time, B 4 C particle size, RHA percentage, percentage porosity in the preforms, and magnesium content in the alloy. The contributions of each of the parameters to the retained porosity, hardness and modulus of elasticity of the resulting bilayer composites were determined. The parameters that most significantly impact the modulus of elasticity ( E ) of the resulting composites are chemical composition of Al alloy followed by porosity of preforms and B 4 C particle size. Their relative contributions to the variance in the values of modulus of elasticity are 25.7, 22.48 and 18.44 %, respectively. Verification tests conducted using the established optimum parameters show a good agreement with those of projected values.