Effect of B-Si ratio and laser remelting on the microstructure and properties of Fe10Co10Ni10Cr4Mo6BxSi10-x coating by laser cladding

Abstract

High-entropy alloy coating has huge potential application values in improving the service life of the friction parts. The effects of the B-Si ratio and laser remelting on the microstructure, phases, mechanical and wear properties of the laser cladding Fe10Co10Ni10Cr4Mo6BxSi10-x coatings were investigated. When x equals 10, the coating crystalizes in a FCC structure together with lots of MxB phases. Si element adding promotes the formation of BCC phase of Fe10Co10Ni10Cr4Mo6BxSi10-x coatings with the appearance of new MxSi and MxBSiy phases, but prevents the formation of MxB and MxBSiy with the decrease of B-Si ratio. When x drops to zero, the microstructure of the coating transforms into a BCC with tiny amounts of FCC and MxSi phase. With the increase of Si element content, Mx(B, Si) standing for any combination of MxB, MxSi and MxBSiy phases decrease. The lowest friction coefficient (0.3786) and wear volume loss (2.46 × 106 μm3) show that Fe10Co10Ni10Cr4Mo6B5Si5 coating has the best wear resistance because of a higher toughness and values of H/E and H3/E2. Laser remelting once reduces the component segregation of the coating, and promotes the formation of BCC and Mx(B, Si) phases. The wear resistance of the coating increases with the improvement of its wear characteristics (H/E, H3/E2 and η). However, when the coating is remelted twice, the wear resistance decreases due to the drop of the hardness and wear characteristics attributed to the dominant position of FCC structure. Fine and uniform microstructure, and proper proportion of hard phases (BCC and Mx(B, Si)) and soft phase (FCC) can increase the mechanical properties and wear resistance of Fe10Co10Ni10Cr4Mo6BxSi10-x coatings.