Tsyganenko N. Influence of alloying on structure and properties of eutectic and hypoeutectic titanium-boride and titanium-silicide-boride alloys

The thesis is devoted to problems of development of new titanium-matrix composites with bor-ide and silicide-boride reinforcements, which are promising for applications as a heat-resistant material and wear-resistant and heat-resistant coating. Systematic studies were carried out for the first time, and the influence of boron content on microstructure and properties of alloys Ti-6Al + 0 2 wt.% В and Ti-6Al-4V + 0 2,5 wt.% В were ascertained. The structure and properties of alloys, the matrix com-positions of those correspond to the high-temperature industrial Ti materials, are examined. Systematic studies of the effect of alloying additions of the p-elements (Al, Si, Ge, Sn) and d-metals (V, Nb, Zr) on the structure and properties of eutectic (hypoeutectic) alloys in the two-phase (Ti) + (TiB) and three-phase adjacent regions of ternary systems Ti-B-X (where X is Al, Si, Ge, Sn, V or Nb); as well as two-phase (Ti) + (TiB) alloys of quaternary Ti-Al-B-X systems (where X is Si, Ge, Sn, Zr, V or Nb) at Al content of 10 at. % were performed for the first time. A ternary phase Ti6Ge2B and three-phase eutectic (Ti) + Ti6Ge2B + (Ti5Ge3) with highly dispersed structure, which is promising for the development of new materials, were firstly found in the Ti-Ge-B system. Systematic studies of the effect of alloying with Al, Sn and Zr on the structure and properties of alloys based on the three-phase eutectic (Ti) + Ti6Si2B + (Ti5Si3) were executed for the first time. Relationships between structure and properties of alloys based on titanium-boride two-phase and titanium-silicide-boride three-phase eutectics were es-tablished. The titanium-silicide-boride alloys with high level of heat-resistance were obtained in the present work. Keywords: titanium matrix composites, eutectic alloys, boride, phase, eutectic, hardness, strength, high-temperature strength, ductility, reinforcement.