Effects of Extrusion on Microstructure and Friction Wear Resistance in situ ZrB2/6063Al Aluminum Matrix Composites

In situ ZrB2/6063Al aluminum matrix composites were prepared by extrusion with 6063Al-(K2ZrF6+KBF4) as the reaction system. The microstructure changes of the composites before and after extrusion were studied, and the influence of extrusion process on the friction and wear properties of the composites was also studied. The results show that for the composite materials prepared by in situ casting, the grain size of the matrix is 30 similar to 50 mu m, and the ZrB2 particles are regular polygons with serious agglomeration. After extrusion processing, the grain size of the composite is fine, between 7 similar to 14 mu m, and the ZrB2 particle size is uniform, between 1 similar to 3 mu m, and agglomeration is improved. Because the particle size distribution is more uniform after extrusion, the particle is rounder and blunter, which makes the surface of the wear scar smoother, and the difference of the concave and convex of each part decreases. The friction coefficient decreases with the increasing of the loading. When the load is 12 N, the minimum friction coefficient is 0.29, which is reduced by 32.4% compared to that of the original ingot of composite materials. The wear volume and wear scar width decrease, and the wear resistance has been also greatly improved. The wear mechanism of the composites is mainly abrasive wear and slight adhesive wear.