The effectiveness of coincidence site lattice criteria in predicting creep cavitation resistance |
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Authors: | F Otto E J Payton J Frenzel G Eggeler |
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Affiliation: | (1) Institut fuer Werkstoffe, Ruhr-Universitaet Bochum, 44780 Bochum, Germany;(2) Present address: Materials Science and Technology Division, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831-6115, USA;(3) Present address: Division 5.1: Composition and Microstructure of Engineering Materials, Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany |
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Abstract: | The coincidence site lattice (CSL) concept is often used in microstructural characterization by researchers studying grain
boundary engineering as a method for improving the performance of polycrystalline materials. It is assumed that a high degree
of shared lattice sites in the boundary between two grains will result in improved mechanical properties. For practical application
of the CSL concept to experimental results, a maximum deviation from ideal CSL orientation relationships must be defined to
distinguish potential CSL boundaries from random boundaries that are not likely to exhibit “special” properties. Several different
maximum deviation criteria have been proposed in the literature. In this study, four of these criteria are investigated for
their effectiveness in predicting the creep cavitation resistance of boundaries of different CSL character in three model
alloys: pure Cu, Cu-Bi, and Cu-Sb. Bi and Sb strongly segregate to Cu grain boundaries and are detrimental to creep life.
The experimental observations are compared to simulation results for a non-textured polycrystal. It is observed that only
boundaries related to cubic annealing twins (Σ3 and Σ9) exhibit special resistance to creep cavitation, that boundaries with
Σ > 3 are affected by the presence of segregants, and that the fraction of non-Σ(3,9) boundaries tracks closely with what
would be expected from a random polycrystal. It is shown that more restrictive criteria result in more reliable characterization
of the fraction of cavitation-resistant boundaries only because they exclude more non-Σ(3,9) boundaries from the analysis. |
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