Microstructure and Texture of Al-Pb Surface Composites Fabricated by Friction Stir Processing

Al-Pb surface composites were prepared by friction stir processing (FSP) to improve their friction and wear properties. The microstructure, texture and hardness distribution of Al-Pb surface composites were analyzed by SEM, EBSD, nano indentation and microhardness tester. The results show that the Pb particles are mainly distributed at the bottom of processing area under the action of gravity and agitation. The onion ring structure is formed by the flow of the plastic material. There are Pb-rich lamellae and deformed aluminum matrix lamellae in the onion ring structure. The Pb particles in the Pb-rich lamellae play an important role in grain refinement. Meanwhile, a small amount of new Pb particles (about 100 nm) form in the deformed aluminum matrix. The grain refinement results show that the microhardness of Pb-rich lamellae is significantly higher than that of deformed aluminum matrix. Furthermore, there are different types of texture in the different zones. At the bottom of the processing area, there is a strong Cube texture on SZ-AS. SZ-RS has Cube texture and a small amount of brass texture, and CSZ has weak Cube texture and {111} texture. At the top, there is a strong Goss texture on AS, and the texture on RS is relatively random.