Abstract
Aluminium-lithium alloys have a great potential in aero-space engineering. Enhancing the physical, mechanical and operational properties of these alloys by alloying provides an important problem. A high interest to these alloys can be explained by the fact that lithium with the density of 0.54 g/cm3 changes the modulus of elasticity of aluminium bringing it higher while reducing the weight of parts made from aluminium alloys. Rare earth metals (REM) added to aluminium alloys can enhance their strength, heat resistance and corrosion resistance. REMs produce a modifying effect leading to a more refined grain. Due to high reactivity of the components introduced in aluminium the production of aluminium-lithium alloys containing rare earth metals may pose certain challenges. Taking this into account, the vacuum resistance furnace of SNEV 1.3.1 / 16 with a helium atmosphere and the overpressure of 0.5 MPa was used to produce the alloys. An XRD analysis and a scanning electron microscope of the STEREOSCAN 440 series (England) were applied to study the alloys in view. A Vickers hardness tester (HV) was used to test the hardness of the alloys. The study confirmed that the addition of REMs can increase the hardness of the parent alloy to 170 HV. Cerium proved to be the most effective addition in terms of hardness and strength. The study of the microstructure of the alloys show that small additions of REMs can produce a modifying effect and result in a refined eutectic structure (α-Al + AlLi) in alloys. Along with eutectic crystallization, the precipitation of Al-REM intermetallic phases was observed in the alloys.
Keywords
Al+6%Li alloy, REM, Vickers microhardness, ultimate strength, microstructure, X-ray spectral analysis.
1. Rioja J., Materials Science and Engineering A257 (1998) 100–107.
2. Gupta R.K., Niraj Nayan, Nagasireesha G., Sharma S.C. Materials Science and Engineering A 420 (2006) 228–234.
3. Betsofen S.Ya., Antipov V.V., Betsofen M.I. et al. Sostav, tekstura I anizotropiya mehanicheskih svoystv splavov Al-Cu-Li и Al-Mg-Li [The composition, the texture and the mechani-cal anisotropy of Al-Cu-Li and Al-Mg-Li alloys]. Deformatsiya i razrushenie materialov [Deformation and failure of materials], 2015, no. 11, pp. 10–26. (In Russ.).
4. Lynch S.P. Wanhill J.H., Byrnes R.T., Bray G.H. Fracture Toughness and Fracture Modes of Aerospace Aluminum–Lithium Alloys / S.P. Lynch // Chapter 13 – pp. 416-456 in book: “Aluminum-Lithium Alloys. Processing, Properties and Applications” Elsivier Inc. 2014. P. 554–558.
5. Saccone A., Cacciamani G., Macci D., Borzone G., Ferro R. Intermetallics, 6. 1998. Р. 201–215.
6. Xu Yue, Geng Jiping, Liu Yufeng. Journal of rare earths, 24. 2006. Р. 793–796.
7. Nazarov Sh.A., Ganiev I.N., Norova M.T., Ganieva N.I., Calliari I. Potentiodynamic study of the Al+6%Li alloy doped with yttrium in NaCl solution. Vestnik Magnitogorskogo Gosudarstvennogo Tekhnicheskogo Universiteta im. G.I. Nosova [Vestnik of Nosov Magnitogorsk State Technical University], 2016, vol. 14, no. 2, pp. 95–100. doi:10.18503/1995-2732-2016-14-2-95-100 (In Russ.).
8. Nazarov Sh.A., Ganiev I.N., Norova M.T., Ganieva N.I., Calliari I. Vliyanie lantana na anodnoe povedenie splava Al +6 % Li [The effect of lanthanum on the anode behavior of the Al+6%Li alloy]. Obrabotka sploshnykh i sloistykh materialov [Processing of solid and composite materials], 2016, no. 1 (44), pp. 49–53. (In Russ.).
9. Journal of Siberian Federal University. Engineering & Tech-nologies 5 (2015 8) P. 636–645.
10. Mirzoev Sh., Eshov B., Badalov A. Fiziko-khimicheskie svoystva alyuminonov RZM tserievoy podgruppy [Physical and chemical properties of the cerium group REM aluminons]. Germany: LAP Lambert Academic Publishing, 2012, 105 p.
11. Wang M.J., Chen L., Wang Z.X. Effect of rare earth addition on continuous heating transformation of a high speed steel for rolls. J. Rare Earths, 2012. 30: 84.
12. Hu X.W., Jiang F.G., Yan H. Effects of rare earth Er additions on microstructure development and mechanical properties of die-cast ADC12 aluminum alloy. J. Alloys Compd., 2012, P. 538–544.
13. Stanford N., Atwell D., Beer A., Daviesc C., Barnett M.R. Effect of microalloying with rare-earth elements on the texture of extruded magnesium-based alloys. Scripta Mater., 2008, 59: 772.
14. Chen K.H., Fang H.C., Zhang Z., Chen X., Liu G. Mater. Sci. Eng.A 497 (2008)426.
15. Son H.T., Lee J.S., Kim D.G., Yoshimi K., Maruyama K. J. Alloys Comp. 2009. P. 446–473.
16. Ganiev I.N., Nazarov Kh.M., Odinaev Kh.O. Splavy alyuminiya s redkozemelnymi metallami [Aluminium alloys with rare earth metals]. Dushanbe: Maorif, 2004, 190 p.
17. Rioja R.J., Liu J. Metallurgical and materials transactions a volume 43A, september 2012, P. 25–33.
18. Shuhong Liu, Yong Du, Hailin Chen, Computer Coupling of Phase Diagrams and Thermochemistry 30. 2006. P. 33–34
19. Savitskiy E.M., Terekhova V.F. et al. Splavy redkozemelnykh metallov [Rare earth alloys]. Moscow: Publishing House of the USSR, Academy of Science, 1962, 268 p. (In Russ.).