Oksana A. The phase diagram and properties of alloys of B-Mo-Ti and B-Mo-Nb systems

The thesis is devoted to investigation of phase equilibria in the ternary systems B-Mo-Ti and B-Mo-Nb. Ternary alloys, both as-cast and annealed at subsolidus temperatures, were studied by a number of techniques. Basing on the experimental data and assessed literature information, phase diagrams at temperatures of melting-solidification were constructed in full concentration ranges as solidus and liquidus surface projections, phase diagram at melting (solidification) and reaction scheme. As a result of thermodynamic modeling by CALPHAD approach, a new version of B-Mo binary phase diagram and ternary B-Mo-Ti one were calculated. The alloys of investigated systems in the metal-boride ranges have high ambient-temperature microhardness and hardness at elevated temperature and are promising for applications as high-temperature materials and heat-resistant coatings. Existence of continuous solid solutions of diborides was predicted in uninvestigated systems B-Mo-Hf and B-Mo-V, continuous solid solutions of monoborides were proposal to form in systems with V and Ta.