Allart, M., Christien, F. & Le Gall, R. (2013) Ultra-fast sulphur grain boundary segregation during hot deformation of nickel. Acta Mater. 61 7938–7946.
Added by: Laurent Cournède (2016-03-10 21:23:29)
|Type de référence: Article
Numéro d'identification (ISBN etc.): 1359-6454
Clé BibTeX: Allart2013
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Mots-clés: alloys, Auger electron spectroscopy (AES), diffusion, Dislocation, dislocations, ductility, Grain boundary segregation, kinetics, Non-equilibrium, precipitation, surface segregation, Vacancy
Créateurs: Allart, Christien, Le Gall
Collection: Acta Mater.
Consultations : 7/488
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Sulphur grain boundary segregation during hot-compression of nickel (5.4 wt. ppm S) is monitored using Auger electron spectroscopy and wavelength dispersive X-ray spectroscopy. The deformation conditions (temperature/deformation rate) investigated are: 550 degrees C/0, 550 degrees C/3 x 10(-5) s(-1), 550 degrees C/3 x 10(-4) s(-1) and 450 degrees C/3 x 10(-5) s(-1). It is shown that plastic deformation accelerates the kinetics of sulphur grain boundary segregation by a factor of similar to 10(3) to a few 10(5), depending on the deformation conditions. Very high levels of segregation (similar to 0.8 monolayer of sulphur) are obtained after very low deformation (similar to 5\%). In addition a linear dependence of the segregation level with time and deformation is demonstrated. The segregation kinetics during plastic deformation is proportional to the deformation rate and almost independent of temperature. Several metallurgical mechanisms are discussed and confronted with the experimental results: dislocations dragging, pipe diffusion, dislocation collection/diffusion and acceleration by excess vacancies. It appears that the models developed in this work on the basis of the two latter mechanisms (dislocation collection/diffusion and acceleration by excess vacancies) predict the experimental data correctly. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Added by: Laurent Cournède