Effects of Si content on the microstructure and properties of CoCrFeMnNiSix high-entropy alloy coatings by laser cladding

The work explored the influences of varying Si content (non-metallic element) on the microstructure, microhardness, wear resistance, and corrosion resistance of high-entropy-alloy coatings. CoCrFeMnNiSix (x = 0, 0.4, 0.8, 1.2, and 1.6) high-entropy-alloy coatings were prepared on the surface of AISI 1045 steel using laser cladding. The microstructure of CoCrFeNiMn consisted of a single FCC solid solution phase without Si addition. With the addition of Si element, the high entropy alloy coating mainly consists of FCC phase, BCC phase and silicide phase structure. The microhardness of CoCrFeMnNiSix high-entropy-alloy coatings increased with increased Si. The average hardness peaked at 513.2 HV0.5 when x = 1.6, which was 1.77 times higher than the Si0 coating without Si addition. The wear resistance of CoCrFeMnNiSix high-entropy-alloy coatings increased with increased Si. The abrasion loss was reduced from 0.0814 to 0.0291 mm3. The main friction and wear mechanisms were adhesive wear, abrasive wear, and oxidative wear. The corrosion resistance of the coating improved with increased Si. The maximum corrosion potential was −0.662 V, and the lowest corrosion current was 2.809 E-6 A/cm2 when Si content was 1.6. The passivation film on the Si1.6 coating surface was the most stable and dense with the optimal corrosion resistance. The work offers a theoretical reference for the preparation of high-entropy-alloy coatings incorporating non-metallic element Si.