Microstructure, Mechanical and Sliding Wear Behavior of AA5083-B4C/SiC/TiC Surface Composites Fabricated Using Friction Stir Processing

摘要

In this research, friction stir processing (FSP) was used to produce three different surface composites of AA5083 reinforced with B4C, SiC, and TiC particles. The effects of reinforced particles and three consecutive FSP passes on particle distribution, microstructure, mechanical and wear properties were studied. The microstructure reveals significant grain refinement with a dense distribution of particulates towards the retreating side and advancing side of stir zone, some region at the centre of stir zone shows particle free bands and excellent bonding between particle and matrix. FSP induces severe plastic deformation promoting mixing and refining the constituent phase in the materials. Mechanical properties and wear resistance of the FSPed samples were evaluated and compared with the matrix alloy. The results show that the incorporation of B4C, SiC and TiC particles into the matrix improves the hardness, tensile and wear properties. TiC and SiC particulates reinforced surface composites reveals a ductile mode of fracture whereas B4C reinforced surface composite shows a bimodal type of fracture. The investigation on wear mechanism was performed using a pin-on-disc tribometer. The results show that the wear mode changes from abrasive to delamination wear.