Obrabotka Metallov. 2017 no. 1(74)

ОБРАБОТКА МЕТАЛЛОВ № 1 (74) 2017 59 МАТЕРИАЛОВЕДЕНИЕ Abstract Titanium aluminides are promising materials for structural and high temperature applications. They possess low density and a high strength level which are very important properties for the aircraft. However, they have a range of disadvantages. Among them, there are low plasticity and crack growth resistance. One of the solutions which allow making use of beneficial properties of intermetallics consists in the formation of intermetallic layers on the surface of metallic samples. In this study the method of non-vacuum electron beam cladding of powder mixtures consisted of aluminium and titanium was used to obtain the surface layers reinforced with intermetallics on cp-titanium work- pieces. Microstructure, microhardness and tribological properties of surface alloyed materials were investigated. An average thickness of coatings was about 2 mm. The microstructure of coatings was characterized mainly by formation of lamellar crystals. The maximum microhardness level of the coatings was about 600 HV. The reasons of microhardness increase consisted in the formation of titanium aluminides and action of the solid solution hardening mechanism. Phase composition of different clads varied from γ-TiAl to α-Ti according toAl percentage in the powder mixture. In comparison with cp-titanium the obtained materials possessed a lower level of a friction coefficient and a lower tendency to adhesion at a contact with a steel indenter. The best results obtained in the process of a sliding fric- tion test were obtained for the Ti-Al(10/35) sample. It possessed 3-4-fold decrease of a friction coefficient compared to pure titanium. Relative wear resistance values obtained during interaction of samples with fixed abrasive particles correlated with their microhardness. Keywords titanium aluminides; electron beam cladding; structure; properties. DOI: 10.17212/1994-6309-2017-1-51-60 References 1. Murray J.L. The Al-Ti (aluminum-titanium) system. Phase Diagrams of Binary Titanium Alloy . Materials Park, Ohio, ASM International, 1987, pp. 12–24. ISBN 0871702487. eISBN 9780871702487. 2. Schuster J.C., Palm M. Reassessment of the binary aluminum-titanium phase diagram . Journal of Phase Equi- libria and Diffusion , 2006, vol. 27, iss. 3, pp. 255–277. doi: 10.1361/154770306X109809 3. Mishin Y., Herzig Chr. Diffusion in the Ti-Al system. Acta Materialia , 2000, vol. 48, iss. 3, pp. 589–623. doi: 10.1016/S1359-6454(99)00400-0 4. Klopotov A.A., Potekaev A.I., Kozlov E.V., Tyurin Yu.I., Aref’ev K.P., Solonitsina N.O., Klopotov V.D. Kristallogeometricheskie i kristallokhimicheskie zakonomernosti obrazovaniya binarnykh i troinykh soedinenii na osnove titana i nikelya [Crystal geometrу and crystal pattern formation of binary and ternary titanium and nickel based compounds]. 2 nd ed. Moscow, Flinta Publ., 2011. 312 p. ISBN 978-5-9765-1214-6. 5. Sahu P. Lattice imperfections in intermetallic Ti-Al alloys: an X-Ray dif-fractions study of the microstructure by the Rietveld method. Intermetallics , 2006, vol. 14, pp. 180–188. doi: 10.1016/j.intermet.2005.05.004 6. Frobel U., Appel F. Strain ageing in γ(TiAl)-based titanium aluminides due to antisite atoms. Acta Materialia , 2002, vol. 50, pp. 3693–3707. doi: 10.1016/S1359-6454(02)00182-9 7. Ivanov V.I., Yasinskii K.K. Effektivnost’ primeneniya zharoprochnykh splavov na osnove intermetallidov Ti3Al i TiAl dlya raboty pri temperaturakh 600–800 °C v aviakosmicheskoi tekhnike [The effectiveness of heat- resistance alloys based on Ti 3 Al and TiAl intermetallics for operation at 600–800 °C in aerospace engineering]. Tekhnologiya legkikh splavov – Technology of light alloys , 1996, no. 3, pp. 63–68. 8. Sims Ch.T., Stoloff N.S., Hagel W.C., eds. Superalloys II: heat-resistant materials for the aerospace and industrial power plants. New York, Wiley, 1987 (Russ. ed.: Supersplavy II: zharoprochnye materialy dlya aerokos- micheskikh i promyshlennykh energoustanovok . V 2 kn. Ed. by Ch.T. Sims, N.S. Stoloff, U.K. Khagel’. Moscow, Metallurgiya Publ., 1995). 9. Huang S.C. Alloying considerations in gamma-based alloys. The 1st International Symposium on Structural Intermetallics : proceedings , Champion, PA, 26–30 September 1993, pp. 299–308. ISBN 0-87339-253-1. 10. Appel F., Paul J.D.H., Oehring M. Gamma titanium aluminide alloys: science and technology . Weinheim, Wiley-VCH, 2011. 745 p. ISBN 9783527315253. eISBN 9783527636204. doi: 10.1002/9783527636204 11. Lazurenko D.V., Bataev I.A., Mali V.I., BataevA.A., Maliutina Iu.N., Lozhkin V.S., EsikovM.A., JorgeA.M.J. Explosively welded multilayer Ti-Al composites: structure and transformation during heat treatment. Materials & Design , 2016, vol. 102, pp. 122–130. doi: 10.1016/j.matdes.2016.04.037 12. Lazurenko D., Mali V., Bataev I., Thoemmes A., Bataev A., Popelukh A., Anisimov A., Belousova N. Metal-intermetallic laminate Ti-Al 3 Ti composites produced by spark plasma sintering of titanium and aluminum