Nb diffusion in ferromagnetic α-Fe

Abstract

The effect of the magnetic ordering on the diffusion of Nb in a-Fe was investigated. Measurements were made in the 673-1073 K, temperature range: using the Secondary Ion Mass Spectrometry (SIMS) as analysis tool. By expanding the temperature range with respect to the previous works, the Arrhenius plot shows the variation of the slope at the Curie temperature and a soft-upward curvature in the ferromagnetic region. The curvature observed is well fitted by the model developed by Ruch et al. The parameter that takes into account the influence of the magnetic order in the vacancy formation and mobility during the Nb diffusion process is quite similar to that observed in other non-magnetic diffusers. A possible explanation for such an effect is given, supported by ab initio calculations.