INFLUENCE OF B4C AND TiN ON THE MICROSTRUCTURE AND WEAR BEHAVIOR OF FRICTION STIR PROCESSED AA7075 SURFACE COMPOSITE

Abstract

Friction stir processing (FSP), which was the advancement in the friction stir welding technique, is thought to be an economic approach to alloying in the solid state that can be used to make composites. In this study, FSP was carried out to produce AA7075 (B4[Formula: see text]iN) composite by varying the composition of the reinforcement particles. Microstructural analysis was carried out and the homogenous distribution of the reinforced particles on the surface of AA7075 alloy was ensured. X-ray diffraction studies were carried out to analyze the phases present after fabricating the hybrid surface composites. Microhardness test was performed on the specimens before and after the fabrication process. Grain refinement in the friction stir processed zones was evidently seen in the optical microstructures. The combined effect of the ceramic powders and grain refinement led to increase in the microhardness in the hybrid surface composites compared with the base AA7075 plate. A 33.87% increase in microhardness was observed in the sample AA7075 reinforced with 75% B4C and 25% TiN. Wear testing was carried out at various loads (5, 10, 15 and 20 N) and at different sliding velocities (300, 350, 400 and 450 rpm) and the track distance was maintained at 1000 m. It was observed that the highest wear rate is [Formula: see text] cm3/Nm for the base plate AA7075 and the sample AA7075 reinforced with 50% B4C and 50% TiN shows the lowest wear rate of [Formula: see text] cm3/Nm. It is observed that the addition of B4C and TiN has resulted in a significant improvement in the wear resistance of the AA7075 alloy.