Effects of selective laser melting process parameters on the fatigue strength and material characteristics of tungsten carbide/inconel 718 composites

Tungsten Carbide (WC)-reinforced Inconel 718 (IN718) composites were prepared by Selective Laser Melting (SLM) technique. The impact of SLM production on WC/IN718 composites was studied to analyze densities, microstructure evolution, tensile properties, and fatigue properties under various process parameters. The effect of parameters on composite densities and powder melting was analyzed by a combination of experimental and simulation methods. In the matrix, the WC particles are dispersed uniformly, and there is a reaction between the WC particles and the matrix to form a good interfacial reaction layer. As the laser energy density increases, the surface of the WC particles melts under high energy density laser irradiation, leading to the diffusion of decomposed W and C atoms into the matrix. Two typical carbides, W₂C and (M, W)C (M for Ni, Cr, Nb, Fe), form sequentially at a distance from the WC grains. At a laser energy density of 89.94 J/mm³, the tensile strength and microhardness of the composites reach the maximum values of 1203 MPa and 403 HV. This is a composite strengthening mechanism resulting from the WC and carbide strengthening phases. The incorporation of WC particles significantly improves the fatigue resistance of the composites compared to IN718. Fatigue fracture is in the form of quasi-dissociation fracture, with fatigue originating from pores and incompletely fused defects on the surface. The fatigue extension zone is characterized by riverine and fatigue streaks. This study offers a theoretical foundation and guidance on enhancing the mechanical properties of nickel-based superalloys and broadening their potential applications in the future.