Microstructure, mechanical and electrical properties of dissimilar friction stir welded 2024 aluminum alloy and copper joints

Abstract

The effect of friction stir welding (FSW) parameters on the microstructure, mechanical and electrical properties of 2024 aluminum alloy and copper joints was investigated. After obtaining the processing window, the optimum values of ultimate tensile strength≈ 142 MPa, elongation≈ 5 %, and electrical resistivity≈ 33 nΩm were obtained by FSW at a rotational speed (W) ≈ 948 rpm and a traverse speed (V) ≈ 85 mm/min. W/V ratio, which stands for the amount of heat input during FSW, had a considerable effect on the joints' properties. At W/V>(W/V)optimum, larger amounts of Al4Cu9 and Al2Cu brittle intermetallic compounds (IMCs), and at W/V<(W/V)optimum, more defects were formed in the joints compared to optimum condition. IMCS and voids in the non-optimum joints were the origin of lower strength and ductility and higher electrical resistivity. Moreover, the mechanism of microstructure formation in the stir zone is discussed in detail.

Keywords

• Friction stir welding
• Al2024
• Copper
• Microstructure
• Mechanical properties