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Stress-controlled carbon diffusion channeling in bct-iron: A mean-field theory

Maugis, Philippe and Chentouf, Sara and Connétable, Damien Stress-controlled carbon diffusion channeling in bct-iron: A mean-field theory. (2018) Journal of Alloys and Compounds, 769. 1121-1131. ISSN 0925-8388

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Official URL: https://doi.org/10.1016/j.jallcom.2018.08.060

Abstract

Diffusion of interstitial carbon atoms in iron is the rate-limiting phenomenon of a number of phase transitions in body-centered (bcc) and body-centered tetragonal (bct) phases such as ferrite and martensite. These phases being rarely stress-free and undeformed, the influence of stress/strain on the diffusivity of carbon is essential, although scarcely documented. We developed a model of carbon elastodiffusion in bct-iron. We combined anisotropic linear elasticity theory of point defects, the dilute approximation of regular solutions and the multisite model of random walk into a coherent mean-field theory. The model allows predicting the effects of composition, temperature and mechanical loading on the anisotropy of carbon diffusion. Density functional theory calculations have provided most of the materials parameters. The predictions were successfully tested against kinetic Monte Carlo simulations. Our results show that compression of the crystal increases carbon diffusivity, while tension has the opposite effect. Axial straining is accompanied by a large anisotropy of diffusion. This effect could be exploited to produce stress-controlled diffusion channeling for the engineering of anisotropic microstructures during thermal ageing of martensitic Fe-C alloys.

Item Type:Article
HAL Id:hal-01993655
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > Aix-Marseille Université - AMU (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Université de Toulon - UTLN (FRANCE)
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Funders:
Agence Nationale de la Recherche- ANR
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Deposited By: cirimat webmestre
Deposited On:25 Jan 2019 08:16

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