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Application of a Modified Jogged-Screw Model for Creep of Titanium Aluminides: Evaluation Of The Key Substructural Parameters

Published online by Cambridge University Press:  10 February 2011

Subramanian Karthikeyan ,
Junho Moon ,
Gopal B. Viswanathan  and
Michael J. Mills
Subramanian Karthikeyan
Affiliation:
Dept. of Materials Science and Engineering, The Ohio State University, Columbus, OH-43210.
Junho Moon
Affiliation:
Dept. of Materials Science and Engineering, The Ohio State University, Columbus, OH-43210.
Gopal B. Viswanathan
Affiliation:
Dept. of Materials Science and Engineering, The Ohio State University, Columbus, OH-43210.
Michael J. Mills
Affiliation:
Dept. of Materials Science and Engineering, The Ohio State University, Columbus, OH-43210.
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Abstract

A modification of the jogged-screw model has been adopted recently by the authors to explain observations of 1/2[110]-type jogged-screw dislocations in equiaxed Ti-48Al under creep conditions. The aim of this study has been to verify and validate the parameters and functional dependencies that have been assumed in this previous work. The original solution has been reformulated to take into account the finite length of the moving jog. This is a better approximation of the tall jog. The substructural model parameters have been further investigated in light of the Finite Length Moving Line (FLML) source approximation. The original model assumes that the critical jog height (beyond which the jog is not dragged) is inversely proportional to the applied stress. By accounting for the fact that there are three competing mechanisms (jog dragging, dipole dragging, dipole bypass) possible, we can arrive at a modified critical jog height. The critical jog height was found to be more strongly stress dependent than assumed previously. The original model assumes the jog spacing to be invariant over the stress range. However, dynamic simulation using a line tension model has shown that the jog spacing is inversely proportional to the applied stress. This has also been confirmed by TEM measurements of jog spacings over a range of stresses. Taylor's expression assumed previously to provide the dependence of dislocation density on the applied stress, has now been confirmed by actual dislocation density measurements. Combining all of these parameters and dependencies, derived both from experiment and theory, leads to an excellent prediction of creep rates and stress exponents. The further application of this model to other materials, and the important role of atomistic and dislocation dynamics simulations in its continued development is also discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 778: Symposium U – Mechanical Properties Derived from Nanostructuring Materials , 2003 , U8.6/W7.6
Copyright
Copyright © Materials Research Society 2002

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References

1. Maziasz, P. J., Ramanujan, R. V., Liu, C. T., and Wright, J. L., Intermetallics 5, (1997).Google Scholar
2. Beddoes, J., Wallace, W., and Zhao, L., Int. Mater. Rev. 40, 197 (1995).Google Scholar
3. Parthasarathy, T. A., Mendiratta, M. G., and Dimiduk, D. M., Scr. Mater. 37, 315 (1997)Google Scholar
4. Wang, J. N. and Nieh, T. G., Acta Mater. 46, 1887 (1998).Google Scholar
5. Sprengel, W., Nakajima, H., and Oikawa, H., Mater. Sci. Eng., A A213, 45–50 (1996).Google Scholar
6. Viguier, B., Hemker, K. J., Bonneville, J., Louchet, F., and Martin, J. L., Phil. Mag. A 71 1295 (1995).Google Scholar
7. Ishikawa, Y. and Oikawa, H., Mater. Trans., JIM (Japan) 35, 336 (1994).Google Scholar
8. Lu, M. and Hemker, K. J., Acta Mater. 45, 3573 (1997).Google Scholar
9. Sriram, S., Dimiduk, D. M., Hazzledine, P. M., and Vasudevan, V. K., Phil. Mag. A 76, 956 (1997).Google Scholar
10. Louchet, F. and Viguier, B., Phil. Mag. A A 80, 765 (2000).Google Scholar
11. Viswanathan, G. B., Vasudevan, V. K., and Mills, M. J., Acta Mater. 47, 1399 (1999).Google Scholar
12. Rosenthal, D., Trans. ASME 68, 849 (1946).Google Scholar
13. Barrett, C. R. and Nix, W. D., Acta Metall. 13, 1247 (1965).Google Scholar
14. Karthikeyan, S., Ph.D. Thesis, The Ohio State University, Columbus, Ohio (2003).Google Scholar
15. Coble, R. L., J. Appl. Phys. 34, 1679 (1963).Google Scholar
16. Nabarro, F. R. N., Rept. Conf. Strength of Solids (Univ. Bristol) 75 (1948).Google Scholar
17. Herring, C., J. Appl. Phy. 21, 437 (1950).Google Scholar
18. Harper, J. and Dorn, J. E., Acta Metall. 5, 654. (1957).Google Scholar
19. Pryzstupa, M. A. and Ardell, A. J., Metall. Trans. A 33, 231 (2002).Google Scholar
20. Weertman, J., Trans. AIME 218, 207 (1960).Google Scholar
21. Nabarro, F. R. N., Phil. Mag. 16, 231 (1967).Google Scholar
22. Weertman, J. R., J. Appl. Phys. 26, 1213 (1955).Google Scholar
23. Weertman, J. R., J. Appl. Phys. 28, 1185 (1957).Google Scholar
24. Nix, W. D. and Ilschner, B., 5th Int. Conf. Strength of Metals and Alloys, 1503 (1979).Google Scholar
25. Viswanathan, G. B., Karthikeyan, S., Hayes, R. W., and Mills, M. J., Metall. Trans. 33A, 329 (2002).Google Scholar
26. Viswanathan, G. B., Karthikeyan, S., Hayes, R. W., and Mills, M. J., Acta Mater. 50, 4965 (2002).Google Scholar
27. Karthikeyan, S., Viswanathan, G. B., Kim, Y.-W., Vasudevan, V. K., and Mills, M. J., ISSI-3, 3rd Inter. Conf. Struct. Intermetallics, 717 (2001).Google Scholar
28. Karthikeyan, S., Viswanathan, G. B., Kim, Y.-W., Vasudevan, V. K., and Mills, M. J., Creep and Fracture of Eng. Mater. and Struct., Proc. Inter. Conf., 55 (2001).Google Scholar
29. Furubayashi, E., J. Phys. Soc. Jap. 27, 130–46 (1969).Google Scholar
30. Vitek, V., Cryst. Lattice Defects 5, 1–34 (1974).Google Scholar
31. Legrand, B., Phil. Mag. A 52(1), 83–97 (1985).Google Scholar
32. Woodward, C., private communication (2003).Google Scholar
33. Ikeno, S. and Furubayashi, E., Phys. Status Solidi a 12, 611 (1972).Google Scholar
34. Ikeno, S. and Furubayashi, E., Phys. Status Solidi a 27, 581 (1975).Google Scholar
35. Garret-Reed, A. J. and Taylor, G., Phil. Mag. A 39, 597 (1979).Google Scholar
36. Low, J. R. Jr and Turkalo, A. M., Acta Met. 10, 215 (1962).Google Scholar