As diffusion in ferromagnetic α-Fe

Abstract

Diffusion of As in α-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 α Q=40 kJ mol⁻¹, diffusion parameters for the paramagnetic region could be extrapolated, these being the pre-exponential factor D ^p₀ =10⁻⁵ m² s⁻¹ and the activation energy Q ^p=197 kJ mol⁻¹.