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"The effect of magnetism on Fe diffusion: New experimental results and ab-initio calculations"
R.A. Perez, D.N. Torres, F. Dyment and M. Weissmann
Proc. of the "6th International Conference on Diffusion in Materials" (DIMAT 2004), Krakow, Poland, July 18-23, 2004.
Defect. Diffus. Forum, Vol.237-240 (2005) 462-467
Diffusion of non-magnetic impurities in α-Fe has been studied in an extended temperature range, usin Ion Beam techniques. In all cases linear Arrhenius plots were obtained in the paramagnetic region, with a break at the Curie temperature (1043 K) and an up-ward curvature in the ferromagnetic region. This behavior is explained in terms of progressive lattice stiffness due to the alignment of the magnetic spins, as in the self-diffusion case. The maximum increment in the activation energy due to the ferromagnetic alignment (that corresponding to 0 K) is almost the same for all the non-magnetic diffusers, around 40 kJ/mol. The conservation of that quantity is also obtained from calculations using the WIEN97 code, which is an implementation of the linearized augmented plane wave (FP-LAPW) method based on density functional theory. In this paper the model is successfully applied to new measurements of As diffusion in ferromagnetic α-Fe. In consequence, such kind of diffusers can be considered as “magnetic vacancies” in the ferromagnetic lattice and the diffusion coefficient at low temperatures of other non-magnetic impurities can be extrapolated from the paramagnetic high temperature region and vice versa.
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