Friction stir welding of SiC particulate reinforced AA2124 aluminium alloy matrix composite

The aim of this work is to demonstrate the feasibility of friction stir welding (FSW) for joining of AA2124/SiC/25p composite materials. Microstructure, microhardness, EDX analysis and electrical conductivity measurements have been performed to evaluate the weld zone characteristics of friction stir welded AA2124/SiC/25p composites. Friction stir welding can be used to join AA2124/SiC/25p composites. The EDX analysis and the microstructure investigations of AA2124/SiC/25p composite demonstrate the presence of both fine and coarse SiC particle reinforced AA2124 matrix alloys. The weld nugget exhibits the relatively homogeneous SiC particle distributions but has fine particle density bands. In addition, the nugget contains some porosity around the coarse SiC particles and cracking of some coarse SiC particles. The thermo-mechanically affected zone (TMAZ), which is adjacent to the weld nugget, has been plastically deformed and thermally affected. TMAZ exhibits the elongated grains of Al alloy matrix and the SiC particle-free regions of the composite. The heat affected zone (HAZ) between TMAZ and unaffected base composite regions exhibit a similar microstructure both at the retreating and advancing sides as the base composite. Electrical conductivity measurements show the differences between the welding zone and base composite.