Effect of heat treatment temperature on microstructure and properties of SiC/FeCoNiCrAl high-entropy alloy composite coatings via laser cladding

Abstract

To optimize the microstructure and performance of laser-cladded 5 wt.% SiC/FeCoNiCrAl high-entropy alloy (HEA) composite coatings, this study investigated heat treatments at 700°C, 800°C, and 900°C. XRD, SEM, and EDS analyses reveal that post-treatment coatings retain a dual-phase FCC and BCC solid solution structure, accompanied by the precipitation of a Cr 2 Fe 14  C phase. The microstructural evolution exhibited a clear temperature-dependent behavior: static recovery predominated at 700°C, complete recrystallization occurred at 800°C with the formation of fine and uniform equiaxed grains, whereas abnormal grain growth occurred at 900°C. With increasing temperature, residual stress shows a non-monotonic trend, reaching a minimum of 272.4 MPa at 800°C, while elemental segregation is effectively mitigated. The 800°C heat-treated coating exhibits the optimal comprehensive performance: the highest microhardness (584 HV 0.5 ), lowest wear rate (1.07 × 10 -5  mm 3 /(N·m)), shallowest wear depth (19.42 μm), and minimal corrosion current density (813.103 μA·cm -2 ), significantly outperforming all other samples. These mechanical and anti-corrosion enhancements stem from the synergistic effects of precipitation strengthening and microstructural homogenization. Ultimately, identifying 800°C as the optimal parameter provides a robust theoretical foundation for applying tailored HEA coatings to mechanical components under severe working conditions.