Strength–wear trade-off in DLMD Stellite 6–SiC coatings

Direct laser metal deposition (DLMD) was used to fabricate Stellite 6 metal–matrix composites reinforced with 0, 5 and 10 wt.% SiC. This study quantifies how SiC content governs the microstructure, tensile response, and tribological performance. Spherical Stellite 6 (53–180 µm) and irregular SiC (3–10 µm) powders were blended and deposited on 17-4PH steel. SiC addition refined dendrites and increased hardness monotonically: the 10 wt.% composite reached HV̄ ≈ 910 (peak ≈ 1041 HV), >60% above unreinforced Stellite 6. Tribology improved accordingly: the 10 wt.% SiC coating showed a ∼6× lower wear volume than the matrix alloy. Conversely, bulk strength exhibited a non-monotonic trend: UTS peaked at 1255 ± 22.9 MPa for 5 wt.% SiC but decreased at 10 wt.% (1180 ± 84.9 MPa), consistent with SiC agglomeration acting as stress concentrators. Fracture and surface analyses link the strength–wear trade-off to particle dispersion and process-induced heterogeneity at higher loading. These results show DLMD can tailor Stellite 6–SiC for application-specific targets: 5 wt.% for load-bearing strength versus 10 wt.% for maximum wear resistance. The study provides a quantitative map of property trade-offs to guide parameter/composition selection in laser-deposited Co-based MMCs.