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.