Conclusions
-
1.
The kinetics of isothermal decomposition of high-temperature β-phase for two-phase martensitic titanium alloys after undercooling from different temperatures are described by typical C-shaped curves; this decomposition may have one or two stages above the MS point. The type of isothermal decomposition diagram for this phase is governed by the alloy heating temperature and the temperature for the start of the martensite β→α″-transformation.
-
2.
An increase in alloy heating temperature into the two-phase region leads to a shift in C-shaped curves in the direction of higher temperatures and shorter exposures, i.e., the decomposition process is accelerated.
-
3.
With isothermal exposure for undercooled alloys in the martensite range it is possible for the martensitic β→α″-transformation to occur. With undercooling to a temperature above MS high-temperature β-solid solution is stabilized and the martensitic β→α″-transformation does not occur during subsequent cooling.
-
4.
Mechanical properties of the alloys are goverved by the mechanism of high-temperature β-phase decomposition. Decomposition by an intermediate mechanism provides high alloy strength, although the ductility is lower. As a result of β-solid solution decomposition by a diffusion mechanism, an alloy has higher ductility with quite high strength. The optimum combination of strength and ductility as well as high property stability is obtained as a result of isothermal exposure for an alloy undercooled from the two-phase region to a temperature corresponding to the maximum rate for β-solid solution decomposition in the first stage.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Literature cited
V. S. Lyasotskaya, T. F. Frolova, and F. S. Mamonova, "Decomposition of metastable phases in α+β-titanium alloys during aging and isothermal treatment,” Izv. Vyssh. Uchebn. Zaved., Tsvetn. Metall., No. 5, 129 (1977).
B. Hocheid et al., C. R. Acad. Sci.268, No. 22, 1936 (1969).
B. Hocheid et al., Mem. Sci. Rev. Metallurg.67, 583 (1970).
T. Andersson, Scand. J. Metallurg.,2, No. 5, 251 (1973).
B. Hocheid et al., "Isothermal transformations of a Ti-6% Al-6% V-2% Sn alloy after preheating in the (α-β) range,” in: Titanium Sci. and Technology, Vol. 3, New York-London (1973), p. 1609.
F. L. Lokshin et al., "Study of isothermal transformation in alloys Ti10V and Ti10V3A1,” Izv. Vyssh. Uchebn. Zaved., Tsvetn. Metall., No. 5, 115 (1976).
E. A. L'vova, M. A. D'yakova, and S. Z. Khabliev, "Mechanism and kinetics of metastable β- and α″-phase decomposition in two-phase titanium alloys,” Izv. Akad. Nauk SSSR, Met., No. 1, 154 (1979).
M. A. D'yakova et al., "Effect of heating temperature before quenching and tempering on phase transformations and properties of titanium alloys VT3-1 and VT9,” Fiz. Met. Metalloved.,42, No. 2, 333 (1976).
B. A. Kolachev, "Phase transformations in titanium alloys,” Izv. Vyssh. Uchebn. Zaved., Tsvetn. Metall., No. 5, 102 (1976).
M. A. D'yakova and E. A. L'vova, "Features of direct and reverse β⇆α″ martensitic transformations in two-phase titanium alloys,” in: Proc. of the Int. Conf. ICOMAT-77, Martensitic Transformations in Metals and Alloys [in Russian], Naukova Dumka, Kiev (1979).
M. A. D'yakova, T. G. Potemkina, and N. A. Krasil'nikova, "Kinetics of phase transformations in alloy VT6,” Fiz. Met. Metalloved.,44, No. 1, 141 (1977).
M. A. D'yakova, T. G. Potemkina, and E. S. Makhnev, "Kinetics of metastable β-phase decomposition in titanium alloy VT9,” Fiz. Met. Metalloved.,45, No. 2, 354 (1978).
Additional information
S. M. Kirov Ural Polytechnic Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 42–47, February, 1982.
Rights and permissions
About this article
Cite this article
D'yakova, M.A., L'vova, E.A. & Potemkina, T.G. Mechanisms of the isothermal decomposition of β-solid solution in two-phase martensitic titanium alloys. Met Sci Heat Treat 24, 128–133 (1982). https://doi.org/10.1007/BF00700941
Issue Date:
DOI: https://doi.org/10.1007/BF00700941