Rapid W/SiC reaction induced by laser surface remelting within SiCf/Ti17 composites

Compared to alloys, metal-matrix composites experience more complicated microstructure evolution and interfacial reactions under extreme thermal conditions during laser additive manufacturing, welding-repairing and laser surface engineering. In this study, a cubic-shaped SiCf/Ti17 composite is heated by laser surface remelting and the rapid W-SiC reaction within the core-section of SiC fiber located in the molten pool were investigated. As fiber location close to the center of laser spot, severe reaction between W-core and SiC was observed. By applying SEM, XRD, nanoindentation and TEM, the reaction products are confirmed to be W2C and W5Si3. The W2C has ellipsoid shape with a P-31m space group ordered structure, while W5Si3 solidify between W2C resulting from its lower melting point. Because of the extreme temperature that melt W5Si3, the reaction products exhibit different morphology from those produced by solid-state diffusion such as sintering.