HIGH TEMPERATURE STRENGTH OF COMPOSITE MATERIAL WITH CELL STRUCTURE ON THE BASIS OF Ni₃Al INTERMETALLIDIDE

The powder metallurgy method was used to obtain materials in the form of a single-phase alloy based on Ni₃Al and in the form of composite material (Ni₃Al + W) with cell structure based on it. The structural unit of the composite material was a round granule (grain) with average size of 25 μm from nickel alloy, on which the continuous tungsten coating with thickness of ~0.4 μm was deposited by chemical vapor deposition. Compression tests at room temperature have shown that the yield stress of composite material (Ni₃Al + W) with cell structure at temperatures of 20 – 1000 °C is higher than of single-phase Ni₃Al-based alloy (up to 1.7 times), but at higher test temperature the yield strength of the composite is compared with the yield strength of the nickel alloy. The specific yield strength (that is, normalized for the density of 7.8 g/cm³ for the alloy and of 9.5 g/cm³ for the compo site) behaves similarly. At the temperature of 1300 °C, single-phase Ni₃Al-based alloy exhibits solid-liquid behavior under compression. Creep tests were carried out for compression under vacuum at temperatures of 1000 – 1200 °C. Using the pair and parametric methods of mathematical analysis of creep processes according to Hollomon, regression equations of creep rate, stress and temperature of the test were obtained. The ultimate strength of creep for the given tolerances for steady-state creep rate and inverse values were calculated. It is shown that at all test temperatures the composite material has lower creep rate (up to 7 times) and higher ultimate strength of creep (up to 2.5 times) than the nickel alloy on which it is based. Creep activation energies of the materials studied are determined using the exponential law of coupling of experimental values. The creep activation energy for the nickel alloy found is close to the activation energy of nickel self-diffusion in Ni₃Al and materials based on it (230 ÷ 310 kJ/mol), and for the composite – to self-diffusion activation energy of tungsten (503 kJ/mol).

1. Belomyttsev M.Yu., Shtremel’ M.A., Medvedev V.V., Mochalov B.V., Chernukha L.G. Structure and properties of composite materials with cell structure based on NiAl intermetallide. Izvestiya. Ferrous Metallurgy. 2006, no. 1, pp. 40–44. (In Russ.).

2. Kimura Y., Pope D.P. Ductility and toughness in intermetallics. Intermetallics. 1998, vol. 6, no. 6, pp. 567–571.

3. Belomyttsev M.Yu., Molyarov A.V., Arsenkin A.M. Crack resistance structure composites of honeycombed NiAl–W(W + Mo)-system. Izvestiya. Ferrous Metallurgy. 2010, no. 9, pp. 41–44. (In Russ.).

4. Belomyttsev M.Yu., Kozlov D.A., Eremin A.V. Effects of environmental and temperature on structure, phase composition and mechanical properties of intermetallics and NiAl-based materials. Message 2. Interacting of materials with oxygen and nitrogen. Izvestiya. Ferrous Metallurgy. 2011, no. 9, pp. 32–38. (In Russ.).

5. Kablov E.N., Buntushkin V.P., Povarova K.B., Bazyleva O.A., Morozova G.I., Kazanskaya N.K. Light low-alloy high-temperature materials based on the intermetallide Ni3 Al. Russian Metallurgy (Metally). 1999, no. 1, pp. 69–75.

6. Ermilov A.G. Metallizatsiya termotsiklirovaniem [Metallization by thermocycling]. Moscow, Saransk: Tip. “Kras. Okt.”, 2006, 256 p. (In Russ.).

7. Ohno T., Watanabe R., Nonomura T. Development of a die material for isothermal forging of superalloys in air. Transactions ISIJ. 1987, vol. 27, no. 1, pp. 34–41.

8. Ohno T., Watanabe R., Fukui T., Tanaka K. Isothermal forging of Waspaloy in air with a new die material. Transactions ISIJ. 1988, vol. 28, no. 11, pp. 958–964.

9. Tabaru T., Hanada S. High temperature strength of Ni3 Al-base alloys. Intermetallics. 1998, vol. 6, no. 7–8, pp. 735–739.

10. Belomyttsev M.Yu. High-temperature tests of intermetallides small samples on compression. Izvestiya. Ferrous Metallurgy. 2000, no. 11, pp. 42–44. (In Russ.).

11. Belomyttsev M.Yu., Eranosov Ya.V., Chertov S.S. Tests of microsamples for short-term creep under compression. Izvestiya. Ferrous Metallurgy. 2005, no. 3, pp. 46–50. (In Russ.).

12. Rozenberg V.M. Rozenberg V.M. Osnovy zharoprochnosti metallicheskikh materialov [Fundamentals of high-temperature strength of metallic materials]. Moscow: Metallurgiya, 1973, 328 p. (In Russ.).

13. Zolotorevskii V.S. Mekhanicheskie svoistva metallov [Mechanical properties of metals]. Moscow: MISiS, 1998, 400 p. (In Russ.).

14. Bernshtein M.L., Zaimovskii V.A. Mekhanicheskie svoistva metallov [Mechanical properties of metals]. Moscow: Metallurgiya, 1979, 496 p. (In Russ.).

15. Khimushin F.F. Zharoprochnye stali i splavy [Heat-resistant steels and alloys]. Moscow: Metallurgiya, 1969, 752 p. (In Russ.).

16. Shlyakman B.M., Yampol’skii O.N., Ratushev D.V. A method for determining constant C in the Hollomon parameter. Metal Science and Heat Treatment. 2011, vol. 52, no. 9-10, pp. 451–453.

17. Garofalo F. Fundamentals of Creep and Creep-rupture in metals. New York and London, 1965. (Russ.ed.: Garofalo F. Zakony polzuchesti i dlitel’noi prochnosti metallov i splavov. Moscow: Metallurgiya, 1968, 304 p.).

18. Čadek Josef. Creep in metallic materials. Prague: Academia, 1988, 372 p. (Russ.ed.: Čadek J. Polzuchest’ metallicheskikh materialov. Moscow: Mir, 1987, 304 p.).

19. Bokstein B.S., Bokstein S.Z., Spitsberg I.T. Ni self-diffusion in alloyed Ni3 Al. Intermetallics. 1996, vol. 4, no. 7, pp. 517–523.

20. Frank S., Rüsing J., Herzig Chr. Grain boundary self-diffusion of 63 Ni in pure boron-dopped Ni3 Al. Intermetallics. 1996, vol. 8, no. 7, pp. 601–611.

21. Bazyleva O.A., Povarova K.B., Kazanskaya N.K., Drozdov A.A. Rare-earth metals in nickel aluminide-based alloys: III. Structure and properties of multicomponent Ni3 Al-based alloys. Russian Metal lurgy (Metally). 2009, no. 2, pp. 154–159.

22. Bokshtein B.S. Diffuziya v metallakh [Diffusion in metals]. Moscow: Metallurgiya, 1978, 348 p. (In Russ.).

23. Miracle D.B. The physical and mechanical properties of NiAl. Acta Metallurica et Materialia. 1993, vol. 41, no. 3, pp. 949–985.

24. Povarova K.B., Bannykh O.A. Principles of creating alloys based on intermetallides. Part I. Materialovedenie. 1999, no. 2, pp. 27–33. (In Russ.).

25. Povarova K.B., Bannykh O.A. Principles of creating alloys based on intermetallides. Part II. Materialovedenie. 1999, no. 3, pp. 29–37. (In Russ.).