The effect of Ti and B4C on the microstructure and properties of the laser clad FeCoCrNiMn based high entropy alloy coating

Abstract

FeCoCrNiMnTix(B4C)y high entropy alloys (HEAs) coatings were laser cladded on Q355 steel using coaxial powder feeding laser 3D printing system by adjusting the additive ratio of pure Ti powder and B4C powder into the pre-alloyed spherical equi-atomic FeCoCrNiMn powder. Hardness, X-Ray Diffraction (XRD) phase composition, Scanning Electron Microscope (SEM) morphology, Energy Dispersive X-ray Spectroscopy (EDS) and wear resistance of the HEAs coatings were examined. The FeCoCrNiMnTix HEAs coatings (x = 0.5, 0.6, 0.8, 1.0) composed of fcc, bcc1 and bcc2 phase, The hardness increased as the Ti adding content increased, which may be attributed to the solution strengthening effect and promoting effect to the formation of bcc1 and bcc2 phase. The addition of B4C induced the formation of compound borides and carbides, and the decreasing of Ti solution in fcc and bcc phases. The phase composition of the FeCoCrNiMnTi0.6(B4C) y coating was mainly fcc, bcc2, borides and carbides. The increase of B4C improved the hardness and bcc2 content in FeCoCrNiMnTi0.6(B4C) y HEAs coating, and the wear resistance increased also to some extent. Among four FeCoCrNiMnTi0.6(B4C)y HEAs coatings (y = 0, 0.2, 0.4 and 0.6), FeCoCrNiMnTi0.6(B4C)0.4 HEAs coatings had the best wear resistance.