Microstructure of laser melt injected WC/TC4 MMC on titanium alloy of aircraft flap track

One of the inherent problems associated with aircraft flap track is the solution to improve its wear resistance. The laser melt injection（ LMI） process has been successfully used to prepare a single crystal WC particles reinforced metal-matrix composite on TC4 alloy. The microstructure evolution and phase composition were investigated by optical microscope,SEM,XRD and EDS. In particular,the influence of scanning speed on the dimensions and morphology of MMC was examined. The results showed that the MMC is sensitive to the scanning speed.It was found that the MMC is mainly composed of WC,TiC,Ti,W₂C and W phases. There are two types of TiC,one is a reaction product in the Ti matrix,another is a reaction layer around the WC particles. The reaction layer is more conductive to the wear resistance,because there is a pinning mechanism in WC particles. In addition,a significant difference in the microstructure and microhardness among MMC different zones was observed.