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Effect of oxidation on the mechanical properties of a NbAl3 alloy at intermediate temperatures

Published online by Cambridge University Press:  31 January 2011

S.V. Raj ,
M. Hebsur ,
I.E. Locci  and
J. Doychak
S.V. Raj
Affiliation:
NASA Lewis Research Center, MS 49-1, 21000 Brookpark Road, Cleveland, Ohio 44135
M. Hebsur
Affiliation:
Sverdrup Technology, LeRC Group, Cleveland, Ohio 44135
I.E. Locci
Affiliation:
NASA Lewis Research Center, MS 49-1, 21000 Brookpark Road, Cleveland, Ohio 44135
J. Doychak
Affiliation:
NASA Lewis Research Center, MS 49-1, 21000 Brookpark Road, Cleveland, Ohio 44135
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Abstract

Although a NbAl3 alloy containing Cr, W, and Y has excellent oxidation resistance above 1440 K, it suffers from severe environmental attack during deformation at intermediate temperatures between 900 and 1100 K. Specimens tested in constant velocity and constant load direct compression tests showed varying degrees of degradation depending on environment (i.e., air or argon), surface finish, stress, and temperature. As a result, there were corresponding differences in mechanical behavior and in the observed microstructures. At high stresses and strain rates, specimens with as-machined surfaces were brittle at and below 1100 K when tested in air but showed fracture strains above 4% when deformed in argon. However, reproducible compressive ductility of 2–3% was attained on polished specimens tested in air. At intermediate stresses, the creep curves showed sudden and periodic increases in strain before the specimens failed catastrophically after about 80 h. Microstructural examination of these specimens revealed extensive oxidation within cracks. Constant load tests conducted at lower stresses below 100 MPa showed an apparent incubation period where the change in the length of the specimen was immeasurably small. Following the incubation period, which typically lasted between 10 and 110 h depending on stress, temperature, and surface condition, specimens increased significantly in length due to oxide growth. In this case, considerable oxide spalling occurred during the course of the test, often leading to a substantial decrease in the cross-sectional area of the specimen. Microstructural observations revealed extensive cracking in the oxide layer and in the matrix, where the cracks had originated at the oxide-metal interface. The effects of environment on the mechanical properties are rationalized with the help of a schematic environmental-deformation mechanism map.

Type
Articles
Information
Journal of Materials Research , Volume 7 , Issue 12 , December 1992 , pp. 3219 - 3234
Copyright
Copyright © Materials Research Society 1992

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References

REFERENCES

1Berkowitz-Mattuck, J. and Rossetti, M., Basic Factors Controlling Pest in High Temperature Systems, NASA CR 125071 (National Aeronautics and Space Administration, Washington, DC, 1971).Google Scholar
2Perkins, R. A., Chiang, K. T., and Meier, G. H., Scripta Metall. 22, 419 (1988).Google Scholar
3Doychak, J. and Hebsur, M.G., Oxid. Metals 36, 113 (1991).CrossRefGoogle Scholar
4Grabke, H. J., Brumm, M., and Steinhorst, M., in High Temperature Intermetallics (The Institute of Metals, London, 1991), p. 81.Google Scholar
5Grabke, H. J., Steinhorst, M., Brumm, M., and Wiemer, D., Oxid. Metals 36, 199 (1991).Google Scholar
6Gauje, G. and Brunetaud, R., Rev. Phys. Appl. 5, 513 (1970).CrossRefGoogle Scholar
7Raisson, G. and Vignes, A., Rev. Phys. Appl. 5, 535 (1970).CrossRefGoogle Scholar
8Schneibel, J. H., Becher, P. F., and Horton, J. A., J. Mater. Res. 3, 1272 (1988).Google Scholar
9Hebsur, M.G., Stephens, J.R., Smialek, J.L., Barrett, C.A., and Fox, D. S., in Oxidation of High-Temperature Intermetallics, edited by Grobstein, T. and Doychak, J. (The Minerals, Metals and Materials Society, Warrendale, PA, 1989), p. 171.Google Scholar
10Perkins, R. A. and Meier, G. H., JOM (formerly J. Metals) 42, 17 (1990).Google Scholar
11Hebsur, M.G. and Stephens, J.R., New Niobium-Aluminum Base Alloys Having Improved High Temperature Oxidation Resistance, U. S. Patent No. 4983 358 (1991).Google Scholar
12Hebsur, M.G., unpublished research.Google Scholar
13Hebsur, M.G., Locci, I.E., Raj, S.V., Nathal, M.V., and Salem, J.A., in HITEMP Review 1990: Advanced High Temperature Engine Materials Technology Program, NASA CP 10051 (Lewis Research Center, Cleveland, OH, 1990), p. 23–1.Google Scholar
14Hebsur, M. G., Locci, I. E., Raj, S. V., and Nathal, M. V., J. Mater. Res. 7, 1696 (1992).CrossRefGoogle Scholar
15Shechtman, D. and Jacobson, L. A., Metall. Trans. 6A, 1325 (1975).Google Scholar
16Doychak, J., Raj, S. V., Locci, I. E., and Hebsur, M. G., in HITEMP Review 1990: Advanced High Temperature Engine Materials Technology Program, NASA CP 10082 (Lewis Research Center, Cleveland, OH, 1991), p. 18–1.Google Scholar
17Binary Alloy Phase Diagrams, edited by Massalski, T. B., Okamoto, H., Subramanian, P. R., and Kacprzak, L. (ASM INTERNATIONAL, Materials Park, OH, 1990), pp. 2748–2749.Google Scholar
18Powder Diffraction File (Inorganic Volume), Joint Committee on Powder Diffraction Standards (JCPDS) (International Centre for Diffraction Data, Swarthmore, PA, 1972–1988).Google Scholar
19Crc Handbook of Chemistry and Physics, edited by Weast, R. C. and Astle, M. J. (CRC Press, Inc., Boca Raton, FL, 1980), pp. B–73.Google Scholar
20Hertzberg, R. W., in Deformation and Fracture Mechanics of Engineering Materials (John Wiley, New York, 1989), 3rd ed., p. 288.Google Scholar
21Berkowitz-Mattuck, J.B., Rossetti, M., and Lee, D., Metall. Trans. 1, 479 (1970).CrossRefGoogle Scholar
22Hillig, W. B. and Charles, R. J., in High-Strength Materials, edited by Zackay, V.F. (John Wiley, New York, 1965), p. 682.Google Scholar
23Aitken, E. A., in Intermetallic Compounds, edited by West-brook, J. H. (John Wiley, New York, 1967), p. 491.Google Scholar