Fabrication and characterization of hybrid surface composite Al5083/Si3N4/TiC using friction stir processing

The fabrication of surface composites via friction stir processing (FSP) is an effective approach to enhance the tribological, mechanical, and corrosion properties of 5083 aluminum alloy (Al5083), thereby extending its service life and broadening industrial applications. In this study, monolithic (Al5083/Si 3 N 4 and Al5083/TiC) and hybrid Al5083/Si 3 N 4 -TiC surface composites with various Si 3 N 4 /TiC volume ratios (50TiC–50Si 3 N 4 , 75TiC–25Si 3 N 4 , and 25TiC–75Si 3 N 4 ) were fabricated using FSP. Microstructural analysis using OM and SEM revealed significant grain refinement, which was further promoted by the addition of reinforcement particles. XRD and EDS analyses confirmed the absence of intermetallic phases; only uniformly dispersed TiC and Si 3 N 4 particles were observed within the aluminum matrix. The Al5083/TiC composite showed the highest hardness, increasing from 74 (base alloy) to ∼150 Vickers. Other samples exhibited hardness values of 85 (FSPed base alloy), 99 (Al5083/Si 3 N 4 ), 117 (25TiC–75Si 3 N 4 ), 132 (50TiC–50Si 3 N 4 ), and 143 Vickers (75TiC–25Si 3 N 4 ). Reciprocating wear tests revealed that Si 3 N 4 imparted superior lubricating effects, resulting in the lowest friction coefficient in Al5083/Si 3 N 4 . Nonetheless, the Al5083/75TiC–25Si 3 N 4 hybrid composite demonstrated the highest wear resistance due to synergistic effects of increased hardness and lubrication. These findings highlight the potential of tailored hybrid surface composites in optimizing Al5083 performance for demanding applications.