KINETICS OF THE INTERACTION OF TITANIUM CARBIDE WITH VANADIUM NITRIDE IN CONDITIONS OF MECHANOCHEMICAL ALLOYING OF TiC—VN BLENDS

Abstract

A detailed X-ray diffraction study of stepwise selected products of mechanochemical treatment in a planetary mill consisting of three mixtures of the TiC—VN system with a ratio of components (mol %) of 2 : 1, 1 : 1 and 1 : 2 has been carried out. It was shown that the mechanochemical activation of these mixtures primarily leads to the accumulation of point defects in them, resulting in the pulverization of crystal structures of titanium carbide TiC and vanadium nitride VN. At the same time, a part of titanium or vanadium atoms moves into the tetrahedral pores of the structures, leaving the metal sublattices vacant. This process is accompanied by the fact that some of the metal atoms leave the TiC or VN structures with the formation of separate clusters of the corresponding metal in the reaction zone of the mill. The formation of separate titanium or vanadium clusters in combination with the accumulation of structural vacancies creates prerequisites for the further formation of mutual solid substitution solutions, the average compositions of which under the given modes of mechanochemical synthesis are (at. %): 47 Ti, 6 V and 47 C for (Ti,V )C; 41 V, 7 Ti and 52 N for (V,Ti)N. The kinetics of the formation process of these solid solutions has been investigated in detail. The final nanocrystalline powders (crystallite size up to 20 nm) of mechanochemically processed TiC—VN mixtures obtained in the work will be tested as additives to improve the functional properties of medical titanium alloys.