  Measurements of Ag radiotracer diffusion in shear bands of deformed bulk
metallic glass, Pd40Ni40P20, [Joachim Bokeloh, Sergiy V. Divinski, Gerrit
Reglitz, and Gerhard Wilde, Phys. Rev. Lett. 107, 235503 (2011).] have found a
colossal enhancement of diffusion coefficient by more than eight orders of
magnitude than in undeformed Pd40Ni40P20. Suggestion was made by Bokeloh et al.
that enhanced diffusion occurs in high-mobility pathways originating from some
excess free volume distribution inside the shear bands. Although plausible,
this qualitative suggestion does not allow quantitative calculation of the
enhancement. The impasse is avoided by using the Coupling Model to calculate
the maximum of the enhancement of diffusivity possible in high-mobility
pathways of the shear bands. Within the range of eight to ten orders of
magnitude, the calculated maximum enhancement is capable to account for the
experimental observation.
