Microstructure Evolution and Properties of a Novel Intermetallics Precipitation-Hardened Steel Coating Reinforced by WC via Laser Cladding

Protecting materials from wear, especially at high temperatures, is crucial across numerous industries. This study develops a novel intermetallics precipitation-hardened Fe–Co–Mo steel composite coating reinforced with WC, in situ intermetallics, and M₆C carbides, designed to achieve superior wear resistance across a wide temperature range. The microstructure evolution, strengthening mechanisms, and dry sliding wear behavior of coatings with varying WC content (0, 10, 20, and 30 wt%) are investigated. Coatings consist of α-Fe, WC particles, and reticular μ and M₆C phases, strengthened by solid solution, second-phase, and grain refinement. Analysis reveals age-hardening behavior, with WC addition influencing the relative content of μ and M₆C phases, affecting peak aging temperature and microhardness. The 10 wt% WC coating exhibits the highest peak microhardness (980 HV_0.2) and an optimal combination of hardness, temper resistance, and wear resistance at both room and elevated temperature, attributed to the balanced formation of μ phases, Laves phases, and M₆C. Higher WC contents lead to excessive coarse M₆C carbide formation, degrading properties. Room-temperature wear resistance improves with increasing WC content, while high-temperature wear resistance initially increases and then decreases, mirroring the trends in peak microhardness and temper resistance.