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Influence of compaction pressure and Si3N4/ZrO2 reinforcement on the properties of aluminium hybrid composites

ABSTRACT In the present study, the aluminium hybrid composites (AHCs) are developed by the powder metallurgy method. Pure aluminium is reinforced with varying weight percentages of ceramic reinforcements (Si3N4 and ZrO2). Pure aluminium powder is mixed with 3 wt% Si3N4 and (0, 1.5, 3 and 4.5 wt%) ZrO2 powder in a centrifugal ball mill at a high speed of 600 rpm for 2.5 hours. The XRD results of the AHC powders shows that no interfacial reaction takes place during the ball milling process. The powder composites are then compacted at three different compaction pressure (340,420 and 500MPa) and sintered in a tube furnace at 500 °C for 30 minutes under an Argon environment. The SEM results of different composites show that the reinforcement and matrix particles are distributed uniformly with the accumulation of nano-size ZrO2 particles. The density and micro-hardness improve with high compaction pressure and weight percentages of the reinforcements but the porosity decreases. The maximum hardness value is found as 72 VHN for sample E (Al+3 wt% Si3N4 + 4.5 wt% ZrO2) at 500 MPa.