Morphology and microstructure of Fe–Cr–W–B alloy powders prepared by argon gas atomization

Abstract

Gas atomization was used to prepare the Fe–W–B and Fe–Cr–W–B alloy powders. The morphology, size distribution, microstructure and fluidity of the alloy powders were examined. Discussion of the effect of Cr on the morphology and microstructure of powders was carried out. The media diameter, flowability and apparent density of atomized Fe–Cr–W–B powders were 81.4 μm, 15.75 s/50g and 5.28 g cm−3, respectively. The gas-atomized powders consisted of α-(Fe,Cr) solid solution, where W and B atoms were dissolved as solute atoms. After heat treatment, (Fe,Cr)W2B2, a stable ternary boride, formed with sufficient atomic diffusion time and energy in the alloy powders. In the Fe–Cr–W–B alloy powders, the Cr elements dissolved into the ternary boride, causing severe lattice distortion and inducing the structure of boride to change from orthorhombic into tetragonal. Moreover, due to the high nucleation rate and low critical nucleation supercooling, the borides in Fe–Cr–W–B powders were more dispersive and tinier (even up to the submicron scale) than Fe–W–B alloy powders. This method can prepare the excellent powder for Fe–Cr–W–B alloy, which can be used as a potential wear-resistant material.