Structure and phase composition of deposited tantalum–carbon films

Abstract

Ion plasma sputtering and the subsequent codeposition of ultrafine tantalum and carbon particles were used to prepare coatings with 4.6–71.5 at % C. Structural studies of the coatings showed the existence of carbon solid solutions in β Ta at carbon contents to 4.6 at %, carbon solid solutions in α Ta at carbon contents of 4.6–10.3 at %, and direct synthesis of TaC at carbon contents of 44.7–71.5 at %. During heat treatments to 700°C, the substantial concentration widening of regions of the existence of Ta₂C and TaC was found. The lattice parameters of hexagonal Ta₂C and fcc TaC carbides were determined for composition ranges of the existence of phases during heating to 700°C. Upon heating above 600°C, the progressive transition of quasiamorphous Ta₂C carbide into the crystalline Ta₂C carbide was found to take place. The possibility of applying the direct synthesis of TaC carbide in engineering was noted.