Phase Transformations in the Ti--6Al--4V Alloy During Hardening in Water and in the High-Pressure Nitrogen Flow

Abstract

The X-ray phase analysis methods with additional application of techniques enhancing the X-ray diagram resolution were introduced to study the phase state of the core and surface layers of the VT6 titanium-based alloy (Ti--6Al--4V) after hardening in water and in the high-pressure nitrogen flow. Rapid cooling from the temperature of 850 °C (from the (α + β) phase region) results in formation of the martensitic orthorhombic phase (α″) and the intermetallic Ti₃Al phase (α₂). The paper shows that volume fractions of the α″- and α₂-phases are higher in the surface layers than in the alloy bulk. Upon subsequent aging, the α₂-phase volume fraction is decreasing in the surface layers, while volume fraction of this phase remains unchanged in the alloy core. During heating and preparation for hardening in the high-pressure nitrogen and water, solid nitrogen and oxygen solutions appear in the α-titanium surface layer, respectively. After hardening in water, titanium dioxide TiO₂ is detected in the surface layer, while after hardening in the high-pressure nitrogen flow, the TiN and Ti₂N phases are found

Please cite this article in English as:

Elchaninova V.A., Aleynikova A.I., Vintaykin B.E., et al. Phase transformations in the Ti--6Al--4V alloy during hardening in water and in the high-pressure nitrogen flow. Herald of the Bauman Moscow State Technical University, Series Natural Sciences, 2025, no. 5 (122), pp. 72--87 (in Russ.). EDN: UWFKND

References

[1] Kazantseva N.V., Krakhmalev P.V., Yadroytseva I.A., et al. Laser additive 3D printing of titanium alloys: current status, problems, trends. Phys. Metals Metallogr., 2021, vol. 122, no. 1, pp. 6--25. DOI: https://doi.org/10.1134/S0031918X21010063

[2] Popova M.A., Popov A.A., Rossina N.G. [Features of the α₂-phase precipitation in heat-resistant titanium alloys]. PROST--2010. Sb. V Evraziyskoy nauch.-prakt. konf. [PROST--2010. Proc. V Eurasian Sci.-Pract. Conf.]. Moscow, MISiS Publ., 2010, p. 7 (in Russ.).

[3] Sahoo R., Jha B.B., Sahoo T.K. Effect of primary alpha phase variation on mechanical behaviour of Ti--6Al--4V alloy. Mater. Sci. Technol., 2015, vol. 31, no. 12, pp. 1486--1494. DOI: https://doi.org/10.1179/1743284714Y.0000000736

[4] Prasad Y.V.R.K., Seshacharyulu T., Medeiros S.C., et al. A study of beta processing of Ti--6Al--4V: is it trivial? J. Eng. Mater. Technol., 2001, vol. 123, no. 3, pp. 355--360. DOI: https://doi.org/10.1115/1.1372708

[5] Popov A.A., Rossina N.G., Zhilyakova M.A. [Processes of α₂-phase precipitation in titanium alloys]. PROST--2018. Sb. tr. IX Evraziyskoy nauch.-prakt. konf. [PROST--2018. Proc. IX Eurasian Sci.-Pract. Conf.]. Moscow, Studio-Print Publ., 2018, p. 20. (in Russ.). EDN: XNERTF

[6] Popov A.A., Popova E.N., Karabanalov M.S., et al. Formation processes of the α + α₂ structure in model pseudo-α-titanium alloys. Phys. Metals Metallogr., 2022, vol. 123, no. 5, pp. 507--512. DOI: https://doi.org/10.1134/S0031918X22050131

[7] Carreon H., Ruiz A., Santovena B. Study of aging effects in a Ti--6Al--4V alloy with widmanstatten and equiaxed microstructures by non-destructive means. AIP Conf. Proc., 2014, vol. 1581, pp. 739--745. DOI: https://doi.org/10.1063/1.4864894

[8] Wei D., Koizumi Y., Nagasako M., et al. Introducing dislocations locally in Al-supersaturated α₂-Ti₃Al single crystal via nanoscale wedge indentation. Intermetallics, 2019, vol. 113, art. 106557. DOI: https://doi.org/10.1016/j.intermet.2019.106557

[9] Agzamov R.D., Tagirov A.F., Nikolaev A.A. Study of influence of low-temperature ion nitriding on the structure and properties of titanium alloy VT6. Vestnik UGATU, 2017, vol. 21, no. 4, pp. 11--17 (in Russ.). EDN: ZWSQJJ

[10] Wielewski E., Siviour C.R., Petrinic N. On the correlation between macrozones and twinning in Ti--6Al--4V at very high strain rates. Scripta Mater., 2012, vol. 67, iss. 3, pp. 229--232. DOI: https://doi.org/10.1016/j.scriptamat.2012.04.026

[11] Li C., Li G., Yang Y., et al. α″ martensitic twinning in alpha + beta Ti--3.5Al--4.5Mo titanium alloy. J. Metall., 2011, vol. 8. DOI: https://doi.org/10.1155/2011/924032

[12] Ilin A.A., Kollerov M.Yu., Ushenin A.V. Zakonomernosti proyavleniya effekta zapominaniya formy v splavakh sistemy Ti--Al--V [Patterns of manifestation of the shape memory effect in Ti--Al--V alloys]. V kn.: Novye stali i splavy, rezhimy ikh termicheskoy obrabotki [In: New steels and alloys, modes of their heat treatment]. Leningrad, DNTP Publ., 1991, pp. 75--76 (in Russ.).

[13] Demakov S.L., Stepanov S.I., Illarionov A.G., et al. Thermal-expansion anisotropy of orthorhombic martensite in the two-phase (α + β) titanium alloy. Phys. Metals Metallogr., 2017, vol. 118, no. 3, pp. 264--271. DOI: https://doi.org/10.1134/S0031918X17030036

[14] Demakov S.L., Semkina Ya.A., Stepanov S.I. [Changing of the orthorhombic martensite lattice parameter in titanium alloy VT23]. Uralskaya shkola molodykh metallovedov. Ch. 1 [Ural School of Young Metallurgists. P. 1]. Ekaterinburg, UrFU Publ., 2016, pp. 219--223 (in Russ.). EDN: YRAEWY

[15] Kuzmin R.N., Vintaykin B.E. Messbauerovskaya spektroskopiya splavov [Mössbauer spectroscopy of alloys]. Moscow, MSU Publ., 1991.

[16] Vintaykin B.E., Kuzmin R.N. Separation of instrumental broadenings and the Kα₂ component and the Kα-doublet on two-dimensional maps of the distribution of X-ray scattering intensity by direct variational methods on a computer. Kristallografiya, 1986, vol. 31, no. 4, pp. 656--660 (in Russ.).

[17] Cherenkov Ya.V., Vintaykin B.E., Smirnov A.E. Investigation of the phase state of the surface layers of high-speed steels based on Fe--W--С after nitriding. Crystallogr. Rep., 2022, vol. 67, no. 4, pp. 602--607. DOI: https://doi.org/10.1134/S1063774522040186

[18] Guinier P. Theorie et teghnique de la radiocristallographie. Paris, Dunod, 1956.

[19] Shevchenko S.Yu., Melnik Yu.A., Smirnov A.E., et al. Comparative evaluation of methods for the determination of heat transfer coefficients of liquid and gaseous quenching media. Mech. Ind., 2017, vol. 18, no. 7, art. 703. DOI https://doi.org/10.1051/meca/2017050

[20] Von Fromm E., Gebhardt E. Gase und kohlenstoff in metallen. Springer, 1976.