Cr mobility in Fe driven by interstitial migration

RAMUNNI, V.P.

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE

SPRINGER

Lugar: Berlin; Año: 2017

1073-5623

Classical and quantum calculations were performed here for characterizing the transport parameters in BCC and FCC Fe-Cr diluted alloys, driven by interstitials. In the same line of ideas as the multi-frequency model, we obtain the relevant transport parameters, namely: i) the involved jump frequencies in the associated multi-frequency model, ii) the full set of phenomenological Onsager coefficients, iii) the tracer correlation factor, iv) the interstitial wind parameter, as well as, v) the tracer self and solute diffusion coefficients. For the BCC phase of the alloy, our calculations include the effects of entropy and ferromagnetic transition in both, the activation energy and the Onsager coefficients. In addition, we perform an extensive study of Fe and Cr migration in the $Sigma 5$ grain boundary structure. We compare present calculations with available experimental data. As is expected, we have found that Cr diffuses mainly via a vacancy mechanism in the bulk of BCC Fe-Cr, while diffusion by interstitials is several orders of magnitudes slower. For the grain boundary, present results show a competition between both, vacancy and interstitial, diffusion mechanisms, which are almost two orders of magnitude higher than in the bulk, in agreement with experiments.