Effect of Friction Stir Processing Pass on Microstructure and Wear Resistance of PI/7075 Aluminum-base Composite

Polyimide (PI) particles were presetted on 7075 aluminum alloy surface, and then friction stir processing (FSP) technique was applied to prepare PI/7075 aluminum-base composite with different processing passes. The effects of the processing pass on the microstructure and wear resistance of the composite were studied. The results show that the inner defects of the composite decreased, and the grain refining effect and the dispersion of the PI particles in the aluminum alloy substrate increased when the processing pass increased. The wear resistance of the composite was better than that of the 7075 aluminum alloy, and increased with the increase of processing pass. The wear surface of the friction stir processed composite with different passes had a few furrows and shallow wear scars, and the wear mechanism was adhesive wear and abrasive wear.