Investigation of Microstructure, Hardness and Intermetallic Compound in Friction stir Welding of AA6065 Aluminum Alloy to Copper

In this study, metallurgical properties lap joint of pure copper and 6065 aluminum alloy with friction stir welding technique were investigated. To purpose the metallurgical properties of joint optical microscopy, X-ray diffraction analysis (XRD), energy dispersive X-ray (EDS) and Vickers hardness junction of micro gauge were used. The results shows that due to the direct contact between aluminum alloy and tool shoulder, the microstructure change of AA6065 was more than copper. With increasing tool rotation speed the microstructure size of AA6065 and copper became smaller and with increasing linear speed and cooling rate, the microstructure size of base material became more. The results shows that the structured layers were formed in stir zone which with increasing heat generation they geometry became thinner and stretcher. The combination of base materials in high tool rotation and low travelling speed caused the CuAl2 and Cu9Al4 intermetallic compounds were formed in base metal interface. For changes in microstructure size and formation of intermetallic compounds, the hardness of stir zone was more than other area of joint. The maximum hardness of joint area was 111 Vickers which allocated to the joint that welded with 1130 rpm and 24mm/min tool speed.