Investigation of the Interphase Interaction at the Interface in the Ti-C System with Domestic Titanium Alloys of the alpha plus beta and Pseudo alpha Classes

摘要

Interaction of Ti-C with titanium alloys of alpha + beta and pseudo alpha classes and formation of the reaction layer at the interface have been investigated. We used titanium alpha + beta alloys VT6 (Ti-Al-V) and VT8 (Ti-Al-Mo-Si) as well as pseudo alpha alloy VT20 (Ti-Al-Zr-Mo-V). The structure and composition of the interfaces were investigated by means of TEM in the scanning beam mode and energy dispersive spectroscopy. It was ascertained that, already at the stage of production of the samples by thermal diffusion joining, interphase chemical interaction and formation of the reaction layers occurred. The reaction layer consists of distinct regions of small crystals (nanocrystals of TiC of 10-50 nm in size) and large grains of Ti8C5 100-500 nm in size. Most of the reaction layer consists of large grains of Ti8C5. It is found that the average thickness of the reaction layer varies depending on the Ti alloy type and is similar to 0.89 mu m (VT6 alloy), similar to 0.97 mu m (VT8 alloy), and similar to 0.51 mu m (VT20 alloy). Additional heat treatment of the samples leads to increasing thickness of the reaction layer in all Ti-C/Ti alloy systems due to the growth of large grains of titanium carbide.