Abstract

IN625-2NbC-2SiC composite coatings were successfully deposited on IN625 substrates using laser cladding technology. This study systematically explores the dependency of phase assemblage, microstructural characteristics, microhardness, and wear behavior on the applied laser power. Experimental results show that the phase composition of the coatings remains essentially unchanged across different power levels, primarily consisting of γ-(Ni, Cr), NbC, and SiC, with partial retention or reprecipitation of NbC particles. Under low laser power, local defects rich in Si and C appear in the coating, which is primarily attributed to insufficient melting or uneven dispersion of SiC particles. An optimal power of 1500 W results in a more homogeneous structure, better elemental distribution, and improved carbide dispersion. However, excessively high laser power may lead to excessive heat input, reduced cooling rate, and local microstructural inhomogeneity. Microhardness and tribological tests demonstrate that laser cladding significantly improves the surface properties of the IN625 substrate. The average microhardness values of the substrate, S1 to S4 are 250.5, 345.4, 357.2, 367.1, and 338.2 HV, respectively. Among them, the S3 coating exhibits the highest microhardness, which is approximately 46.5% higher than that of the substrate. Meanwhile, the S3 coating shows the lowest average friction coefficient and wear rate. The wear resistance ranking is as follows: S3 > S2 > S1 > S4 > substrate. The superior wear resistance of S3 is largely due to its high hardness, uniform structure, and well-distributed carbide reinforcements, which strengthen its resistance to deformation and abrasive wear. Based on overall consideration of phase, microstructure, and tribological performance, 1500 W is concluded to be the optimal laser power under the conditions investigated.

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