Elastic stress in single crystal Ni-base superalloys and the driving force for their microstructural evolution under high temperature creep conditions
- Hitachi Ltd., Omika, Hitachi (Japan). Hitachi Research Lab.
Microstructural stability of blade materials used in land based gas turbine systems has become a critical issue for the reliability and economy of entire power generation systems since the materials must be sound during increasingly longer intervals between inspections. A mechanism for rafting in Ni-base superalloys under high temperature creep conditions is discussed in terms of elastic strain energy. The elastic deformation is analyzed by the finite element method and approximate analytical expressions are also deduced for it. The difference between the elastic strain energies at {gamma} channels parallel and perpendicular to the stress axis is derived in closed form, which is used to evaluate the local equilibrium concentration of component elements. The rate of rafting estimated with a simple diffusion model and the concentration distribution data obtained in the present theory agree well with the magnitude of the measured growth rate.
- OSTI ID:
- 509129
- Journal Information:
- Acta Materialia, Vol. 45, Issue 5; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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