High-Quality WC-Reinforced Inconel 625 Metal Matrix Composite Coating Fabricated by Novel High-Speed Directed Energy Deposition

High-speed directed energy deposition (HS-DED) was employed to fabricate a high-quality tungsten carbide (WC)-reinforced Inconel 625 metal matrix composite (MMC) coating on 316L stainless steel. The exceptionally high scanning speed (~30,000 mm/min) significantly reduced thermal exposure during processing, promoting uniform WC particle retention, negligible porosity (<0.1%), and strong metallurgical bonding with the substrate. Microstructural characterization using SEM, EBSD, and XRD revealed a refined Inconel 625 matrix with limited WC dissolution and pronounced accumulation of geometrically necessary dislocations (GNDs), indicating strong heterogeneous deformation-induced strengthening. The resulting coating exhibited high hardness, superior shear bond strength (623 MPa), and a defect-free structure, outperforming conventional high-velocity oxy-fuel (HVOF)-sprayed coatings. These results demonstrate that HS-DED enables the fabrication of dense, well-bonded, and mechanically robust MMC coatings, offering a promising alternative to conventional thermal spray technologies for demanding wear and structural applications.