Microstructure and properties of Cf + TiB2/7075-modified layer by friction stir processing

Abstract

This study was aimed at preparing a modified layer by implanting Cf + TiB2 mixed particles into the 7075 aluminum alloy using the friction stir processing (FSP) technology. The microstructure, hardness, and wear resistance of the FSP-modified area with different process parameters were studied by microstructure analysis, hardness test, and friction and wear test. The results showed that the grains were refined and distributed evenly; the hardness was improved, especially in the central part of the region; and the friction coefficient was smaller in the FSP-modified region in comparison with the that of the base metal under different process parameters. Moreover, the wear form of the base material and the FSP-modified area was "furrow + adhesion" comprehensive wear form, in which the base metal was mainly adhesive wear and the FSP-modified area was mainly furrow wear. The grain refinement and hardness of the FSP-modified region obtained at a rotation speed of 1000 rpm and a forward speed of 10 mm/min were improved, and the wear resistance was the best.