National University of Science and Technology "MISIS" (MISiS)

N. A. Belov, Professor, e-mail: nikolay-belov@yandex.ru

V. D. Belov, Head of a Chair of Casting Processes Technology (CPT)

Vertical and isothermal sections of multicomponent systems on the base of titanium (Ti – Al – V, Ti – Al – Nb and Ti – Al – Cr – V) as applied to grade casting alloys were calculated using the Thermo-Calc software. The temperatures of liquidus (T_l), solidus (T_s) and transition into β-region at heating (T_β) are given for some alloys. Calculated values of T_l, T_s and T_β for alloys VT6L, VT14L and VT9L at three temperatures (600, 800 and 900 ^оС) are given. They show that alloys VT6L and VT14L at all temperatures contain only two phases: α and β. Alloy VT9L with a small addition of silicon contain phases TiZrSi and Ti₅Si₃ also. Using the alloy VT6L as an example it was shown that the value of T_β has a significant difference (more than 60 ^оC) inside grade chemical composition. Analogous calculations were made as applied to grade alloys on the base of titanium aluminides. They show that the alloy alpha-2 in the temperature range 700–900 ^оС has single phase microstructure (AlTi₃). The alloy super alpha-2 in the same temperature range contain a small amount of phase β. By the totality of the calculated and previously obtained experimental data, it is concluded that a quantitative analysis of phase composition is a power tool for elaboration of casting alloys on the base of titanium and titanium aluminides with improved combination of service and technological properties.

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2. Kolachev B. A., Elagin V. I., Livanov V. A. Metallovedenie i termicheskaya obrabotka tsvetnykh metallov i splavov : 4-e izd (Metallography and heat treatment of non-ferrous metals and alloys : 4-th ed). Moscow : MISIS, 2005. 432 p.

3. Polmear I. J. Light Metals: From Traditional Alloys to Nanocrystals : 4^th edit. Elsevier, 2005. 421 p.

4. Vojtěch D., Popela T., Hamáček J., Kützendörfer J. The influence of tantalum on the high temperature characteristics of lamellar gamma + alpha 2 titanium aluminide. Mater. Sci. and Engineering A. 2011. Vol. 528. pp. 8557–8564.

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8. Belov N. A. Diagrammy sostoyaniya troynykh i chetvernykh sistem : uchebnoe posobie dlya vuzov (Constitution diagrams of ternary and quaternary systems : tutorial for institutes of higher education). Moscow : MISIS, 2007. 360 p.

9. Kolachev B. A., Ilin A. A. Izvestiya vuzov. Tsvetnaya metallurgiya – Russian Journal of Non-Ferrous Metals. 2005. No. 6. pp. 56–61.

10. Belov N. A. Fazovyy sostav promyshlennykh i perspektivnykh alyuminievykh splavov (Phase structure of industrial and prospective aluminium alloys). Moscow : MISIS, 2010. 511 p.

11. Belov N. A. Izvestiya vuzov. Tsvetnaya metallurgiya – Russian Journal of Non-Ferrous Metals. 2010. No. 3. pp. 45–52.