Autonomous Repair Mechanism of Creep Damage in Fe-Au and Fe-Au-B-N Alloys

The autonomous repair mechanism of creep cavitation during high-temperature deformation has been investigated in Fe-Au and Fe-Au-B-N alloys. Combined electron-microscopy techniques and atom probe tomography reveal how the improved creep properties result from Au precipitation within the creep caviti...

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Bibliographic Details
Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2015-12, Vol.46 (12), p.5656-5670
Main Authors: Zhang, S., Kwakernaak, C., Tichelaar, F. D., Sloof, W. G., Kuzmina, M., Herbig, M., Raabe, D., Brück, E., van der Zwaag, S., van Dijk, N. H.
Format: Article
Language:English
Subjects:
Alloys
Autonomous
Characterization and Evaluation of Materials
Chemistry and Materials Science
Creep (materials)
Damage
Deformation
Gold
Grain boundaries
Holes
Materials Science
Metallic Materials
Metals creep
Nanotechnology
Precipitation
Repair
Structural Materials
Surfaces and Interfaces
Thin Films
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Summary:The autonomous repair mechanism of creep cavitation during high-temperature deformation has been investigated in Fe-Au and Fe-Au-B-N alloys. Combined electron-microscopy techniques and atom probe tomography reveal how the improved creep properties result from Au precipitation within the creep cavities, preferentially formed on grain boundaries oriented perpendicular to the applied stress. The selective precipitation of Au atoms at the free creep cavity surface results in pore filling, and thereby, autonomous repair of the creep damage. The large difference in atomic size between the Au and Fe strongly hampers the nucleation of precipitates in the matrix. As a result, the matrix acts as a reservoir for the supersaturated solute until damage occurs. Grain boundaries and dislocations are found to act as fast transport routes for solute gold from the matrix to the creep cavities. The mechanism responsible for the self-healing can be characterized by a simple model for cavity growth and cavity filling.
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-015-3169-9