材料期刊网

Nanocrystalline compound TiC has been synthesized by mechanically alloying (MA) the starting Ti-50 at.% C powder mixtures. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the structural evolution of Ti50C50 during milling. The changes of the grain size and the internal strain for different phases were determined as a function of milling time. Under the employed condition, TiC formed when milling for 10 h and its amount increased with milling time. After 27 h milling, TiC formed completely with a grain size of 9 nm, which was ill good agreement with the TEM observation, and the internal strain of TiC reached 2.4%. It is suggested that the reaction is controlled by the interdiffusion of elements, especially the contribution of C atoms. The large negative heat of formation for TiC nor only provides a driving force to the reaction but also favors the reaction by increasing the diffusivity of C atoms.