First-principles calculations of rare earth (Y, La and Ce) diffusivities in bcc Fe

• The impurity diffusivities of Y, La and Ce in bcc Fe have been investigated.
• Y and La more favorably bond to the 1nn vacancy.
• The trend in diffusivities is DY > DLa > DCe.

The impurity diffusivities of rare earth elements, Y, La and Ce, in bcc Fe have been investigated by the first-principles calculations within nine-frequency model. The microscopic parameters in the pre-factor and activation energies have been calculated. For the three elements, the first nearest-neighbor solute-vacancy interactions are all attractive, in which Y and La solute atoms more favorably bond to the vacancy. The solute-vacancy binding energy can be explained in terms of the combination of the distortion binding energy and the electronic binding energy, and the decomposition results of the total solute-vacancy binding energy suggest that the strain-relief effect accounts for larger portion of the binding energy for Y and La than that for Ce. The diffusion coefficients of Y are one order of magnitude larger than that of La, and predicted to be comparable to that of Fe self-diffusion. Compared with Y and La, Ce shows large migration energy and small solute-vacancy attractive interaction, which accounts for the lowest diffusivity of this element.