Phase Equilibria Investigation of Binary, Ternary, and Higher Order Systems. Part I. The Phase Diagrams of The Systems Ti-Nb-C, Ti-Ta-C, and Ti-Mo-C

摘要

The ternary alloy systems Ti-Nb-C, Ti-Ta-C, and Ti-Mo-C were investigated by means of X-ray, melting point, DTA, and metallographic techniques and phase diagrams for all three systems from 1500C through the melting range were established. The solid state phase relationships in all three systems are similar. The cubic monocarbides are completely miscible, whereas the subcarbides, Nb(Ta,Mo)C2 show limited solubility and are terminated by three-phase equilibria Me + Me2C + MeC1-x in the ternary. The sublattice order-disorder transition in the subcarbides are lowered by titanium substitutions. The monocarbide solutions in all three systems show a regular melting behavior. The phase relationships of the three systems are discussed and the differences in particular equilibria related to the thermodynamic properties of the phases in the boundary systems. (Author)