Effect of Elastic Driving Force on the Evolution of Microstructures in the Secondary Creep Stage

Article Preview

Abstract:

The effect of elastic driving force on the microstructural change of superalloys in the secondary creep stage is evaluated by elastic energy calculations with the concept of effective eigen strain where both lattice mismatch and creep strain are taken into account The elastic energy calculations indicates that the elastic state in the secondary creep stage is totally different to that in the initial one where the lattice misfit between γ and γ' phases is over accommodated along the [100] and [010] directions by creep deformation in the γ phase. The excess creep dislocations for the over accommodation are required so as to develop an internal stress field to prevent further creep deformations. The planer raft structure with the plane normal oriented to the [001] direction is unstable in the over accommodated state. The γ/γ' lamellar interfaces will be inclined to make a wavy raft structure of which elastic energy is lower than the ideal 001 planer raft structure.

You have full access to the following eBook

Info:

[1] J.K. Tien and R.P. Gramble: Metall. Trans. Vol. 3 (1972), p.2157.

Google Scholar

[2] D.D. Pearson, F.D. Lemkey and B.H. Kear: Superalloys 1980 (The Minerals, Metals & Materials Society 1980), p.513.

Google Scholar

[3] A. Epishin, T. Link, P.D. Portella and U. Brückner: Acta Mater., Vol. 48 (2000), p.4169.

Google Scholar

[4] K. Tanaka, T. Kajikawa, T. Ichitsubo, M. Osawa, T. Yokokawa and H. Harada, Mater. Sci. Forum, Vol. 475-479(2005), p.619.

DOI: 10.4028/www.scientific.net/msf.475-479.619

Google Scholar

[5] S. Socrate and D. M. Parks: Acta Metall. Mater., Vol. 41 (1993), p.2185.

Google Scholar

[6] J.Y. Buffiere and M. Ignat: Acta Metall. Mater., Vol. 43 (1995), p.1791.

Google Scholar

[7] F.R.N. Nabarro, C.M. Cress and P. Kotschy: Acta Mater., Vol. 44 (1996), p.3189.

Google Scholar

[8] N. Matan, D.C. Cox, C.M.F. Rae, R.C. Read: Acta Mater., Vol. 47 (1999), p. (2031).

Google Scholar

[9] T. Ichitsubo and K. Tanaka: Acta Mater., Vol. 53 (2005), p.4497.

Google Scholar

[10] G. Colonnetti: Atti Accard Naz Lincei Rc, Vol. 24 (1915), p.404.

Google Scholar

[11] L. Müller, U. Glatzel and M. Feller-Kniepmeier: Acta Metall. Mater., Vol. 41 (1993), p.3401.

Google Scholar

[12] T.M. Pollock and A.S. Argon: Acta Metall. Mater., Vol. 40 (1992), p.1.

Google Scholar

[13] A.G. Khachaturyan: Theory of Structural Transformation in Solids, (Wiley, New York, 1983).

Google Scholar

[14] T. Ichitsubo, D. Koumoto, M. Hirao, K. Tanaka, M. Osawa, T, Yokokawa and H. Harada: Acta Mater., Vol. 51 (2003), p.4863.

DOI: 10.1016/s1359-6454(03)00326-4

Google Scholar