STUDY OF TiN/Ti COMPOSITE MATERIAL BY REACTIVE CO₂ LASER DIRECT SYNTHESIS IN SITU

TiN/Ti composite material was prepared with high power CO₂ laser focused on the surface of titanium alloy in nitrogen ambient. The microstructure, composition and micro hardness of the material were analyzed with SEM, XRD, EP (electron probe) and Micro hardometer. The results show that nitride layers consist of TiN and α-Ti phase. TiN dendrites distribute in nitride layer homogeneously. The nitride level and maximum micro hardness increase with reaction time increasing. The cross section micro hardness of the material changes continuously. The higher laser energy density, the deeper nitride layers. The depth of nitride layer and the surface micro hardness are 350μm and Hv1600 as the laser power density is of 3.35×10⁵ W·cm^-2 , scanning velocity of 300mm·min ^-1 , and nitrogen pressure of 0.35MPa respectively.