W diffusion in paramagnetic and ferromagnetic α-Fe

Abstract

Diffusion of W in the 723–1153 K temperature range both in paramagnetic and ferromagnetic α-Fe was studied, diffusion couples were manufactured by W evaporation onto high-purity Fe samples. Measurements were made using the Heavy Ion Rutherford Backscattering (HIRBS) technique as the analysis tool. A straight Arrhenius plot was obtained in the paramagnetic region with a break at the Curie temperature (1043 K) followed by a curved plot at lower temperatures as a product of the effect of ferromagnetism on diffusion. A straight Arrhenius plot was obtained in the paramagnetic region with a break at the Curie temperature (1043 K) followed by a curved plot at lower temperatures resulting from the effect of ferromagnetism on diffusion. A previous developed model for the diffusion of non-magnetic impurities in ferromagnetic Fe fits the data perfectly well, giving a temperature dependent diffusivity according to $$\everymath{\displaystyle}\begin{array}{rcl}D(T) &=& 2.3 \times 10^{- 6}\\[5pt]&&{}\times \exp \biggl[ - \frac{( 215~\mathrm{kJ}\,\mathrm{mol}^{-1} )\!\times\! ( 1 + 0.176s^{2} )}{RT} \biggr]~\mathrm{m}^{2}\,\mathrm{s}^{-1}\end{array}$$