To address the challenge of poor wear resistance on the surface of Inconel718 (In718), this study employed laser cladding technology to fabricate Mo-enriched composite coatings on In718 substrates. During the cladding process, nitrogen gas was used as the shielding atmosphere to prevent oxidation and to assist in the in-situ formation of nitrides. A series of comprehensive characterization techniques were employed to evaluate the structural and tribological properties of the coatings, including X-ray diffractometer (XRD) for phase identification, scanning electron microscopy (SEM) for microstructural analysis, microhardness testing, and high-temperature friction and wear tests.

The results demonstrated that the primary phases present in the cladded layers included the matrix phases Ni-Cr-Co-Mo and (Fe, Ni) solid solution, as well as hard phases such as Mo₂N and elemental Mo. The microstructure of the coatings was characterized by a dendritic morphology, where long, directionally aligned dendrites were clearly observed, and secondary phase particles were dispersedly dispersed in the interdendritic regions. The metallic Mo were the newly generated Mo particles in the melt pool. Microzone orientation was formed around the Mo particles, which led to further refinement of the grain size. The maximum microhardness of the coating reached 645 HV_0.5, which is approximately 2.8 times higher than that of the In718 substrate (230 HV_0.5). This substantial enhancement in hardness was primarily attributed to solid solution strengthening induced by the Mo element and the synergistic effects of hard phases like Mo₂N.

The wear surfaces of the coatings exhibited the formation of MoO₃ during the frictional process at elevated temperatures. MoO₃, which is known for its layered crystal structure, contributed to significant friction reduction due to its excellent solid lubrication characteristics. As a result, the coefficient of friction (COF) for the Mo-enriched cladded layer was as low as 0.37. The predominant wear mechanism was identified as abrasive wear, accompanied by mild oxidative wear.

The findings reveal the effect of Mo content on the microstructure and tribological performance of laser-cladded In718 coatings. The study offers a theoretical and experimental foundation for future optimization of cladding process parameters in engineering applications requiring enhanced surface wear resistance.