The microstructural characteristics, mechanical and wear behaviour of Aluminium matrix hybrid composites
reinforced with alumina, rice husk ash (RHA) and graphite were investigated. Alumina, RHA and
graphite mixed in varied weight ratios were utilized to prepare 10 wt% hybrid reinforced Al-Mg-Si alloy
based composites using two-step stir casting. Hardness, tensile properties, scanning electron microscopy,
and wear tests were used to characterize the composites produced. The results show that Hardness
decreases with increase in the weight ratio of RHA and graphite in the composites; and with RHA content
greater than 50%, the effect of graphite on the hardness becomes less significant. The tensile strength for
the composites containing o.5wt% graphite and up to 50% RHAwas observed to be higher than that of the
composites without graphite. The toughness values for the composites containing 0.5wt% graphite were
in all cases higher than that of the composites without graphite. The % Elongation for all composites
produced was within the range of 10e13% and the values were invariant to the RHA and graphite content.
The tensile fracture surface morphology in all the composites produced was identical characterized with
the presence of reinforcing particles housed in ductile dimples. The composites without graphite
exhibited greater wear susceptibility in comparison to the composite grades containing graphite. However
the wear resistance decreased with increase in the graphite content from 0.5 to 1.5 wt%.