Synergistic strengthening by in-situ eutectic microstructure and carbide precipitates on tribological performance and oxidation resistance in laser-deposited SiC-IN718 composites

Abstract

This study demonstrates that incorporating 2 wt% SiC particles into Inconel 718 (IN718) via laser metal deposition (LMD) induces significant microstructural and mechanical enhancements through in situ reactive synthesis. During processing, SiC fully decomposes, with liberated carbon preferentially forming Cr₂₃C₆ carbides via Cr segregation, while silicon reacts with Ni and Nb to generate a refined (γ + NiSi + NiSi₂ + NbSi₂) eutectic network. These phase transformations suppress Laves phase formation and modify its morphology compared to monolithic IN718. The optimized composite exhibits superior mechanical performance: tensile strength increases by 1.5× (from 183 HV to 294 HV), wear resistance improves by 85% in material loss reduction, and high-temperature oxidation resistance enhanced by 57.7% (1.51 mg/cm² vs. 2.72 mg/cm² after 100 h at elevated temperatures). The synergistic effects of carbide dispersion strengthening, eutectic refinement, and Laves phase control establish a novel paradigm for ceramic-reinforced nickel superalloy design via additive manufacturing-driven reactive metallurgy, offering critical insights for extreme-environment structural applications.