Synthesis of B4C and BN reinforced Al7075 hybrid composites using stir casting method

Abstract

In the present study an effort has been made to synthesize B4C and BN reinforced Al7075 hybrid composites using stir casting method by varying its weight percentage (3%, 6% and 9%) of B4C and keeping (3%) of BN constant for marine applications. Morphology of the synthesized aluminum hybrid composite and reinforced particle distribution was studied in detail using optical microscopy. It virtually shows the homogeneous distribution of the reinforcement particles in the base metal matrix and it forms Al3BC, AlB12 and AlN as interfacial reactions. Vickers micro-hardness test has been carried out to evaluate the hardness of hybrid composites. It has been found that with increase in percentage of reinforcement the hardness of the synthesized hybrid composites found to be increased compared with the Al7075 base matrix alloy. Mechanical testing has been carried out on the cast composites specimen of different compositions. It has been inferred that addition of reinforcement B4C and BN to base metal matrix added 22% strength to the hybrid composites. ASTM E9 standard has been used to evaluate the compressive properties of hybrid composites and it has been found that inclusion of harder reinforcement tends to resist the load applied and hence the compression properties of such hybrid composites has been improved. ASTM-B117 has been used to study the corrosion behavior of hybrid composites. The corrosion rate decreased by 18.5% between 3% and 6% boron carbide addition whereas it decreased by 22.4% between 6% and 9% boron carbide addition.