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High-temperature creep of single-crystal nickel-based superalloy : microstructural changes and effects of thermal cycling

Viguier, Bernard and Touratier, Fabienne and Andrieu, Eric High-temperature creep of single-crystal nickel-based superalloy : microstructural changes and effects of thermal cycling. (2011) Philosophical Magazine, 91 (35). 4427-4446. ISSN 1478-6435

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Official URL: http://dx.doi.org/10.1080/14786435.2011.609151


Creep tests were performed on MC2 single crystal superalloy at 950°C/200 MPa and 1150°C/80 MPa under isothermal and thermal cycling conditions with a tensile axis along the [0 0 1] direction. It was found that the thermal cycles strongly affect the creep behavior at 1150°C but not at 950°C. This was related to the repetitive precipitation and dissolution of small γ′ rafts at the higher temperature, as revealed by quantitative characterization of the γ/γ′ microstructure. The dislocation microstructure exhibits similar trends in all the tested conditions, with a very high activity of a[1 0 0]-type dislocations climbing through the rafts. Such climbing dislocations constitute a recovery process for the deformation active system. It appears that the density of a[1 0 0] dislocations, and not their climb velocity or diffusion rate, is the key parameter for the control of creep rate. The thermal cycles, which imply the creation and subsequent dissolution of rafts, provided new dislocations, which explains the acceleration of creep observed under such conditions.

Item Type:Article
Additional Information:Thanks to Taylor & Francis editor. The original version is available at http://www.tandfonline.com/The original PDF of the article can be found at Philosophical Magazine website: http://www.tandfonline.com/doi/abs/10.1080/14786435.2011.609151?tab=permissions#tabModule
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Deposited On:08 Jun 2012 09:44

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