Growth characteristics and mechanism of carbides precipitated in WC-Fe composite coatings by laser induction hybrid rapid cladding

WC-reinforced Fe matrix composite coatings were prepared by laser induction hybrid rapid cladding (LIHRC). X-ray diffraction (XRD) was used to identify the phases and the growth characteristics of the precipitated carbides were observed by environmental scanning electron microscope (ESEM). The results show that WC particles are almost dissolved completely and interact with Fe-based alloy liquid in the molten pool to precipitate M6C carbides with different shapes during LIHRC. With increasing the weight percent of WC particles, the transition from the fine M6C carbides, which are precipitated in an intergranular network of the coarse alpha-Fe, to the coarse herringbone M6C eutectics and the primary faceted dendritic M6C occur and the partially dissolved WC particles with an alloyed reaction layer can be occasionally found in the composite coating. Moreover, the eutectic M6C carbides in herringbone shape grow in terms of the intergrowth mode of layer and slice, while the primary faceted dendritic M6C in equiaxial branched shape are only precipitated in the crossed region of the coarse eutectic carbides and grow in terms of dissolution and propagation. (c) 2010 Elsevier B.V. All rights reserved.