Diffusion-plasticity coupling during selective oxidation of metal alloys

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The aim of the project is to study the effect of plastic deformation on bulk and grain boundary diffusion in model binary and ternary Ni-Cr-based alloys (Ni-Cr, Ni-Cr-Fe) in a temperature range including low temperatures where the bulk diffusion cannot be easily measured (350-750 °C). Diffusion coefficients of chromium, nickel and iron will be measured by a combination of two methods to get reliable data: secondary ion mass spectrometry (SIMS) using stable isotopes (France) and the radiotracer technique (Germany). The experiments will be carried out at various temperatures (i) without strain or pre-strain; (ii) on pre-strained samples in order to study the effect of the dislocation network and its evolution during diffusion experiment and, (iii) on specimens during creep to study the influence of dislocation motion. Finally, the measured diffusion coefficients will be integrated in an oxidation kinetics code in order to take into account the effect of plastic deformation in the Cr selective oxidation phenomenon. The following partners will be involved in the project: ARMINES acting through the Centre des Matériaux (CDM) common research centre of ARMINES and MINES ParisTech (coordinator, France), CEA (France) and University of Münster (Germany).