Parametric investigation of Al5456/BNi-2 composite properties fabricated by friction stir processing

Abstract In the present research, surface of 5456 aluminum alloy plate was reinforced by BNi-2 particles via single-pass friction stir processing (FSP). Effects of pin geometry, traveling speed, rotation direction of pin and groove shape were evaluated on influx of reinforcing particles into the stir zone, reinforcing distribution quality, stir zone configuration, using statistical analyzer methods. Hardness and bending tests were also performed for better qualifying of the due evolutions. The results showed that distribution of reinforcement improves by decreasing of pin traveling speed, as the best particle distribution was achieved at 10 mm/min speed. The samples which friction stirred at 30 mm/min traveling speed, provided a fair combination of uniform reinforcement dispersion, finer microstructure and higher hardness. The samples which processed by triangular pin illustrate a sound macrostructure, while the reinforcement is the least in these samples. Moreover, samples which processed with a step-shape groove resulted in almost sound macrostructure with higher bending strength, acceptable particle dispersion and finer grain microstructure. Counter clockwise rotating of the pin during FSP provided higher bending strength due to thread-like shape of the stir zone. The main reason for strength loss in some samples was presence of wormhole defect in the stir zone.