The effects of Nb on the microstructure and performance of laser-cladded Fe50-xMn30Co10Cr10Nbx high entropy alloy coatings

Abstract

A laser cladding technique was employed to produce a Fe50-XMn30Co10Cr10NbX (X = 2.5, 5, 7.5, 10at%) high entropy alloy coating. This study delved into the influence of Nb concentration on the coating’s phase constitution, microstructural features, hardness, and wear resistance. The high entropy alloy coating exhibited a multifaceted structural composition, encompassing FCC (Face-Centered Cubic), HCP (Hexagonal Close-Packed), and BCC (Body-Centered Cubic) structures, along with the presence of Laves phase. Notably, the incorporation of Nb led to an augmentation in the Laves phase and modifications within the microstructure. The hardness of the cladding layer is higher than that of the substrate. With the increase of Nb content, the hardness of the cladding layer increases first and then decreases; the average hardness of the Fe42.5Mn30Co10Cr10Nb7.5 cladding layer is the highest, the maximum hardness is 429.8Hv, and the average hardness is 382.3Hv. The friction coefficient and weight loss of the cladding layer decreases first and then increases with the increase of Nb content. The friction coefficient and weight loss of the Fe42.5Mn30Co10Cr10Nb7.5 cladding layer are the smallest, which are 0.0132 g and 0.5974, showing the best wear resistance. The wear types of high entropy alloy cladding layer are both adhesive wear and abrasive wear. The addition of Nb into high entropy alloy will form the Laves phase, which can improve the mechanical properties of high entropy alloy.