2020 Volume 67 Issue 10 Pages 563-570
TiC-Ti-W-Mo alloy and TiC-Ti-(Ti,W)C-Mo2C alloy were prepared through powder metallurgy. The microstructure of the TiC-Ti-(Ti,W)C-Mo2C alloy was significantly smaller than that of the TiC-Ti-W-Mo alloy. It was considered as follows. Firstly, carbon in W and/or Mo containing carbides is diffused into α-Ti, and then W and Mo phases with vacancies precipitate from carbides. Secondly, they are easily diffused into α-Ti, and then α-Ti is transformed to β-Ti at lower temperature than 1155 K, at which pure Ti transforms. Thirdly, when TiCx particles precipitate in β-Ti, their growths are suppressed by dissolved W and Mo in β-Ti. Furthermore, in the first step above, (Ti,W)C particles are decomposed into super fine (Ti,W)Cx and W phases. From these, it was considered that the carbides grain size of the TiC-Ti-(Ti,W)C-Mo2C alloy is significantly smaller than that of the TiC-Ti-W-Mo alloy. Sintered and HIP treated TiC-Ti-(Ti,W)C-Mo2C alloy has better mechanical properties than those of TiC-Ti-W-Mo alloy.
