Mechanochemical Synthesis of TiN/TiB_2 and TiN/TiSi_2 Nanocomposite Powders via High Energy Ball Milling

摘要

TiN/TiB_2 and TiN/TiSi_2 nanocomposite powders have been mechanochemically synthesized from Ti/BN and Ti/Si_3N_4 powder mixtures, respectively, employing high-energy ball milling. These composite powders are formed by displacement reactions between titanium and nitrides during milling. These reactions exhibit a self-propagating character. The as-milled powders have been characterized using X-ray diffraction and transmission electron microscopy. After the reactions, the crystallite sizes of both powders decrease continuously during milling down to about 10 nm. The annealing of the as-milled TiN/TiSi_2 powders leads to crystallite coarsening and appearance of C49 TiSi_2. It is found that the structure of TiSi_2 changes from C49 to C54 between 900 and 1000°C.