Diffusion of W in paramagnetic and ferromagnetic α-Fe was studied at 723 to 1153K. Diffusion couples were prepared by W evaporation onto high-purity Fe samples. Measurements were performed using the heavy ion Rutherford back-scattering technique. A straight Arrhenius plot was obtained in the paramagnetic region, with a break at the Curie temperature (1043K), followed by a curved plot at lower temperatures. A previously developed model for the diffusion of non-magnetic impurities in ferromagnetic Fe fitted the data well:

D(m2/s) = 2.3 x 10-6exp[-(215kJ/mol)(1+0.176s2)/RT]

R.A.Pérez, D.N.Torres: Applied Physics A, 2011, 104[1], 329-33