As diffusion in ferromagnetic α-Fe

Diffusion of As in á-Fe was studied. Diffusion couples were formed by ion implantation; measurements were made in the 673–1073 K temperature range using the heavy ion Rutherford backscattering (HIRBS) technique as the analysis tool. A curved Arrhenius plot was obtained, as a product of the ferromagnetism effect on diffusion; the previously developed model for diffusion of non-magnetic impurities in ferromagnetic Fe fits the data perfectly well. As diffusion is, on average, two orders of magnitude faster than self-diffusion given its smaller atomic radius (110 pm against 140 pm for Fe). Assuming a total increment in the activation energy due to the ferromagnetic alignment áQ = 40 kJ mol−1, diffusion parameters for the paramagnetic region could be extrapolated, these being the preexponential factor Dp0= 10−5 m2 s−1 and the activation energy Qp = 197 kJ mol−1.