Interfacial Characteristics Of SiC_f/Ti-6Al-4V Composites By Laser Cladding And Performance Study

SiC_f/Ti-6Al-4V composite material will have great application prospect in the field of high-end equipment manufacturing due to its light weight and excellent performance.Different from foil-fiber-foil（FFF）,fiber coating（MCF）and other traditional preparation methods,this research group uses laser cladding lamination technology,which has the characteristics of rapid cooling and rapid heating,so that the element diffusion time between SiC fiber and metal is short,and the uniformity of interface and the interface products are difficult to control.Firstly,using the laser cladding laminated composite additive manufacturing system and optimized process parameters,SiC fiber with C coating and SiC fiber without C coating made in China were adopted.Unidirectional fiber reinforced SiC_f/Ti-6Al-4V sheet composites and 30 mm×20 mm rectangular sample panels of SiC_f/C/Ti-6Al-4V sheet composites with thickness of about 1 mm were prepared.Secondly,the microstructure,composition and thickness of interfacial reaction layer and diffusion of matrix and fiber elements of SiC_f/Ti composites under short-term thermal exposure at 900℃and 950℃were analyzed by optical microscope,scanning electron microscope,transmission electron microscope and energy dispersive spectrometer.The results show that although the forming time of SiC_f/Ti-6Al-4V composites is short,the interface reaction between SiC fiber,C coating and matrix also takes place,and the interface reaction product is mainly Ti C.Compared with SiC_f/Ti-6Al-4V without C coating,the fiber C coating can effectively inhibit the fiber surface damage and protect the fiber.The frequency factor k₀ and activation energy Q of the reaction are slightly increased.Then,nano indentation instrument and microhardness instrument were used to analyze the micromechanical properties of the composites.Through the tensile fracture and interface bonding strength,it was found that the hardness and elastic modulus of SiC fiber,C coating,matrix and interface reaction layer did not change significantly after short-time vacuum high temperature thermal exposure.It shows that the material has good short-term thermal stability at 900℃and below.The elastic modulus of C coating is between Ti-6Al-4V and SiC,which can effectively avoid stress concentration in SiC fiber to a certain extent.Finally,the SiC_f/Ti-6Al-4V composite was tested by electronic universal material tensile testing machine.It is found that the longitudinal tensile strength of composites decreases slightly due to the defects of brittle interfacial products,low fiber content and poor fusion.