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Transformation Toughening Simulated at Different Length Scales

Published online by Cambridge University Press:  15 February 2011

P. C. Clapp ,
Y. Zhao  and
J. A. Rifkin
P. C. Clapp
Affiliation:
Center for Materials Simulation, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136, USA
Y. Zhao
Affiliation:
Center for Materials Simulation, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136, USA
J. A. Rifkin
Affiliation:
Center for Materials Simulation, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136, USA
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Abstract

The microscopic mechanism of “transformation toughening” is thought to be the stress reduction at a crack tip resulting from a displacive phase transformation induced by the stress field of a crack under external loading. Whether transformation toughening or “transformation embrittlement” is the result depends on many different characteristics of the displacive transformation, as well as the geometry of the stress field of the crack. Since both crack and displacive transformation dynamics are sufficiently rapid to be suitably simulated in a molecular dynamics scheme we have explored this approach with the ordered intermetallic NiAl, employing Embedded Atom Method (EAM) potentials. These potentials, in turn, have allowed the construction of a Ginzburg-Landau strain free energy functional (with all the material dependent parameters determined from molecular dynamics simulations) which may then be used to carry out Monte-Carlo simulations of the crack-transformation zone interaction on a substantially larger spatial scale. The simulations reported here show the complex microstructure involving self-accommodating martensite variants which result from the stress induced martensitic transformation near a crack tip in NiAl, and also measure the resulting reduction of stress intensity factor due to the transformation. It is concluded that current continuum mechanics models of transformation toughening need to be substantially revised if they are to adequately model the size, shape and microstructure of the transformation zone and produce accurate predictions of transformation toughening.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 350: Symposium U – Intermetallic Matrix Composites III , 1994 , 299
Copyright
Copyright © Materials Research Society 1994

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References

1 Green, D. J., Hannink, R. H. J., and Swain, M. V. (1989), Transformation Toughening of Ceramics, CRC Press, Inc, Florida.Google Scholar
2 Kim, D. - Ph. D. Thesis, Univ. of Connecticut (1993)Google Scholar
3 Becquart, C. - Ph. D. Thesis, Univ. of Connecticut (1993)Google Scholar
4 Kim, D., Clapp, P. C. and Rifkin, J. A. - MRS Symposia Proceedings, 288, 507–12(1993)Google Scholar
5 Becquart, C. S., Clapp, P. C. and Rifkin, J. A. - MRS Symposia Proceedings, 288, 519–24(1993)Google Scholar
6 Becquart, C. S., Kim, D., Rifkin, J. A. and Clapp, P. C. - Mat. Sci. and Eng. 2, 1–8 (1994)Google Scholar
7 Clapp, P. C., Shao, Y. and Rifkin, J. A. MRS Symposia Proceedings, 246, 1–10 (1992)Google Scholar
8 Shao, Y. - Ph. D. Thesis, Univ. of Connecticut (1993)Google Scholar
9 Chen, S., Clapp, P. C. and Rifkin, J. A., MRS Symposia Proceedings 238, 65–72 (1992)Google Scholar
10 Clapp, P. C., Becquart, C. S., Kim, D., Shao, Y. and Rifkin, J. A., J. Mater. Sci. Technol., 9, 355–9 (1993)Google Scholar
11 Zhao, Y. - Ph. D. Thesis, Univ. of Connecticut (1993)Google Scholar
12 Guenin, G. and Clapp, P. C., Proc. of the International Conference on Martensitic Transformations (ICOMAT), Japan Institute of Metals, pp. 171–179 (1986)Google Scholar
13 Clapp, P. C., Physica D 66, 26–34 (1993)Google Scholar
14 Cao, W., Krumhansl, J. A., and Gooding, R. J., Phys. Rev. B, 41, p. 319, (1990).Google Scholar
15 Chan, S. K., J. Chem. Phys. 67, 5755–5762 (1977)Google Scholar
16 Barsch, G. R. and Krumhansl, J. A., Phys. Rev. Let., 53, p. 1690, (1984)Google Scholar
17 Metropolis, N., Rosenbluth, A. W., Rosenbluth, M. N., Teller, A. H., Teller, E., J. Chem. Phys., 21, p. 1087, (1953)Google Scholar
18 Voter, A. F. and Chen, S. P., Mat. Res. Soc. Proc., p. 3997, (1986).Google Scholar
19 Zhao, Y., Clapp, P. C. and Rifkin, J. A. - to be published, see also ref (11)Google Scholar
20 Daw, M. S. and Baskes, M. I., Phys. Rev. B29, p. 6443, (1984)Google Scholar
21 Meguid, S. A., ”Engineering Fracture Mechanics”, Elsevier Applied Science, London (1989)Google Scholar
22 Evans, A. G. and Cannon, R. M., Acta Metall., 34, p. 761, (1986)Google Scholar