Effect of B4C nanoparticles on microstructure and properties of laser cladded IN625 coating

IN625 is a nickel-based super alloy with remarkably high temperature corrosion resistance, which makes it a good choice for marine and chemical industry applications. However, its relatively low hardness and low wear resistance limit its applications in many areas. In order to increase hardness and wear resistance of laser cladded IN625 coating, B4C nanoparticles were used to reinforce the cladded coating. B4C nanoparticles and IN625 powder were alloyed mechanically under the work of high-energy ball milling. Laser cladded samples were tested for hardness and high temperature friction and wear. OM, XRD, SEM, EDS and EPMA were used for analyzing the microstructure, elemental distribution and wear morphology. The B-C-Cr phase of the powder was produced by high-energy ball milling. The precipitation of Ni3B and Cr3C2 phases in the interdendritic region, refined dendritic structure. The results demonstrated that cladded coating without cracks can be obtained when the B4C nanoparticles content is less than 2 wt%. Elemental analysis showed that the boride reinforced phase was distributed uniformly along a boundary in a molten pool to form B-enriched belts. Mechanical tests showed that the hardness of reinforced layers were increased by about 64% and the high temperature wear volume of B4C nanoparticles reinforced coating was decreased by about 86% compared to the pure IN625 coating. •This study investigated the effect of different contents of B4C nanoparticles on IN625 coating by laser cladding.•High energy ball milling was used for mechanical alloying of nano-B4C and nickel based powder.•Boron element tends to accumulate in some enrichment belts in laser cladded layer.•IN625+2% B4C nanoparticles composite coating showed simultaneous enhanced hardness and wear resistance.