| ArticleName |
High-strength Al – Cu – Li-alloys with increased fracture toughness intended for aircraft structures |
| Abstract |
This paper shows an overview of publications and some results of research of phase composition, grain structure and properties of semi-finished products, made of aluminium-lithium alloys of Al – Cu – Li system, which were additionally alloyed with Zn, Ag, Zr, Sc and Mg. There is considered an offer to divide the aluminum-lithium alloys in two groups:
— 2.0–3.0% of Cu with 1.2–1.8% of Li;
— 3.5–4.5% of Cu with 0.6–1.3% of Li.
V-1461 (В-1461) alloy and similar 2099 (2199) alloys belong to the first group. At the same time, V-1469 (В-1469) and 2060 alloys belong to the second group. It should be taken into account that V-1461 and V-1469 alloys were developed in Russia, when 2099 (2199) and 2060 alloys were developed abroad. Depending on the content of Cu and Li as basic alloying elements, the following phases may precipitate: δ'(Al3Li), θ'(Al2Cu), TB (Al7Cu4Li), Т1(Т'1) (Al2CuLi) and T2 (Al6CuLi3). Diagrams of phase transformations at aging of V-1461 and V-1469 alloys within a wide “temperature – time” range are presented along with the phase areas, providing the maximum strength. Similar results were obtained according to the phase composition of foreign 2199 (2099) and 2060 alloys. There is given the strengthening degree, provided by each strengthening phase. The causes of decreasing of ductility and fracture toughness of aluminum-lithium alloys were analyzed along with the description of their resolving ways. The following factors may be considered as a basic cause of lowered ductility, fracture toughness, sharp strain texture and considerable anisotropy of mechanical properties:
— the strain localization near the grain boundaries, caused by cutting of particles of the main strengthening phase (δ') by dislocations;
— strong texturing of the fibrous structure.
Conditions, which eliminate the strain localization and decrease the texture sharpness, were created in the new generation alloys due to some decreasing of lithium content, addition alloying with Zr, Sc and Mg and application of multi-step aging. Chemical compositions of alloys and conditions of semi-finished products manufacturing were adjusted using the foregoing factors, including thermal and mechanical treatment. Conditions of multi-step aging were developed for the purpose of provision of increased fracture toughness level. There are given the properties of V-1461, V-1469, 2199 (2099) and 2060 alloys with rather high characteristics of fracture toughness. |
| References |
1. Antipov V. V., Kolobnev N. I., Khokhlatova L. B. Razvitie alyuminiy-litievykh splavov i mnogostupenchatykh rezhimov termicheskoy obrabotki (Development of aluminium-lithium alloys and multi-stage thermal treatment regimes). Aviatsionnye materialy i tekhnologii : yubileynyy nauchno-tekhnicheskiy sbornik (Aviation materials and technologies : anniversary scientific and technical collection). Moscow : VIAM, 2012. pp. 183–195.
2. Kolobnev N. I., Khokhlatova L. B., Antipov V. V. Tekhnologiya legkikh splavov — Light alloys technology. 2007. No. 2. pp. 35–38.
3. Khokhlatova L. B., Kolobnev N. I., Oglodkov M. S., Mikhaylov E. D. Metallurg — Metallurgist. 2012. No. 5. pp. 31–35.
4. Fridlyander I. N., Grushko O. E., Antipov V. V., Kolobnev N. I., Khokhlatova L. B. Alyuminiy-litievye splavy (Aluminium-lithium alloys). Aviatsionnye materialy (Aviation materials). 2007. pp. 163–171.
5. Khokhlatova L. B., Kolobnev N. I., Antipov V. V., Karimova S. A., Rudakov A. G., Oglodkov M. S. Vliyanie korrozionnoy sredy na skorost rosta treshchiny ustalosti v alyuminievykh splavakh (Influence of corrosion environment on rate of growth of fatigue cracks in aluminium alloys). Aviatsionnye materialy i tekhnologii : nauchno-tekhnicheskiy sbornik (Aviation materials and technologies : scientific and technical collection). Moscow : VIAM, 2011. No. 1. pp. 16–20.
6. Magnusen P. E., Mooy D. C., Yocum L. A., Rioja R. J. The Minerals, Metals and Materials Society. 2012. pp. 535–540.
7. Karabin L. M., Bray G. H., Rioja R. L., Venema G. The Minerals, Metals and Materials Society. 2012. pp. 529–534.
8. Dorin T., Dtschamps A., Gtuser F. D., Weyland M. The Minerals, Metals and Materials Society. 2012. pp. 1155–1160.
9. Shih J. C., Weyland M., Muddle B. C. Proceedings of the 12th International Conference on Aluminium Alloys. 2010. pp. 2028–2033.
10. Fridlyander I. N., Chuistov K. V., Berezina A. L., Kolobnev N. I. Alyuminiy-litievye splavy. Struktura i svoystva (Aluminium-lithium alloys. Structure and properties). Kiev : Naukova dumka, 1992. 192 p.
11. Khokhlatova L. B., Kolobnev N. I., Oglodkov M. S., Lukina E. A., Sbitneva S. V. Metallovedenie i termicheskaya obrabotka metallov — Metal Science and Heat Treatment. 2012. No. 6. pp. 20–23.
12. Sainfort P., Dubost B. Journal de Physique. 1987. Vol. 48, No. 9. pp. 407–413.
13. Martin J. W. Annual Review of Materials Science. 1988. Vol. 18. pp. 101–119.
14. Oglodkov M. S., Khokhlatova L. B., Kolobnev N. I., Alekseev A. A., Lukina E. A. Vliyanie termomekhanicheskoy obrabotki na svoystva i strukturu splava sistemy Al – Cu – Mg – Li – Zn (Influence of thermomechanical processing on properties and structure of Al – Cu – Mg – Li – Zn system alloy). Aviatsionnye materialy i tekhnologii : nauchno-tekhnicheskiy sbornik (Aviation materials and technologies : scientific and technical collection). Moscow : VIAM, 2010. No. 4. pp. 7–11.
15. Klochkova Yu. Yu., Grushko O. E., Lantsova L. P., Burlyaeva I. P., Ovsyannikov B. V. Osvoenie v promyshlennom proizvodstve polufabrikatov iz perspektivnogo alyuminiylitievogo splava V1469 (Industrial scale mastering of semi-finished products, made of prospective V1469 (В1469) aluminiumlithium alloy). Aviatsionnye materialy i tekhnologii : nauchnotekhni cheskiy sbornik (Aviation materials and technologies : scientific and technical collection). Moscow : VIAM, 2011. No. 1. pp. 8–12.
16. Berezina A. L., Kolobnev N. I., Chuistov K. V. Tekhnologiya legkikh splavov — Light alloys technology. 1992. No. 4. pp. 9–15.
17. Brodusch B., Trudeau M. L., Michaud P. et al. The Minerals, Metals and Materials Society. 2012. pp. 23–28.
18. Khokhlatova L. B., Kolobnev N. I., Samokhvalov S. V. Proceedings of the 11-th International Conference on Aluminium Alloys. 2008. pp. 234–240.
19. Lukina E. A., Alekseev A. A., Antipov V. V. et al. Proceedings of the 12-th International Conference on Aluminium Alloys. 2010. pp. 1673–1678.
20. Boselli J., Bray G., Rioja R. J., Mooy D. et al. The Minerals, Metals and Materials Society. 2012. pp. 581–586.
21. Khokhlatova L. B., Oglodkov M. S., Ponomarev E. K. Metallurgiya mashinostroeniya — Metallurgy of Machinery Building. 2012. No. 3. pp. 22–26. |
