Mechanical properties and formation mechanism of Ti/SiC system gradient materials fabricated by in-situ reaction laser cladding

Ti/SiC system gradient materials were designed and fabricated by in-situ reaction laser cladding technique using Ti and SiC powder. The microstructures of the gradient material were analyzed by a scanning electron microscope (SEM) and an oxford energy dispersive spectrometer (EDS). An X-ray diffraction (XRD) spectrometer was used for determination of the reaction products in the composite layers. It was found that chemical reactions took place between Ti and SiC in the clad layers, and the reaction products included TiC, Ti5Si3, Ti5Si4, TiSi2, and Ti3SiC2. Some residual SiC particles were observable in the gradient layers with SiC volume of no less than 50%. A delamination phenomenon occurred at the 70%Ti+30%SiC layer within the 6.6 mm thickness FGM sample. Finally, a FGM sample with the total thickness of 1.5 mm was successfully fabricated without evident defects and it was believed that the “ductile” Ti3SiC2 phase played an important role in the good forming of the FGM. The average three-point bending strength of the overall TC4/90%SiC FGM was 286 MPa at room temperature, and the microhardness of the outermost layer reached 1607.9HV.