Synthesis of nano (Ti,W)C powder with preferred orientation and twin boundary structure

(Ti,W)C is a novel additive for high performance cermets. In this study, (Ti0.88W0.12)C with the lowest formation energy is synthesized by carbothermal reduction-carbonization in Ar. The starting materials included WO2.72 with one-dimensional nanostructure, TiO2 and carbon black. The phase transition temperatures were established by thermal analysis. XRD analysis results disclose that once TiC is formed at a temperature over 1220 °C, W atoms begin to diffuse into the TiC lattices, which is independent of the existing form of tungsten. At a condition of 1500 °C for 180 min, W and C atoms from the decomposed W2C and WC are fully dissolved in the TiC lattices. Under such a TiC-centered atomic reconfiguration environment, the as-synthesized powder is featured with a BET particle size of 76 nm and texture coefficients TC(111) of 1.53 and TC(200) of 1.33. Results from SEM and HRTEM reveal that the roughly equiaxed powder particles have characteristics of readily identified twin boundary structure and stacking faults. Microscopic inhomogeneity of W solution atoms is discussed. The revelation of the easily identified twin boundary structure and stacking faults is of great significance to the hard phase regulation for high performance Ti(C,N)-based cermets.