An explanation of the differences in diffusivity of the components of the metallic glass Pd_(43)Cu_(27)Ni_(10)P_(20)

摘要

Bartsch [Phys. Rev. Lett. 104, 195901 (2010)10.1103/PhysRevLett.104.195901] reported measurements of the diffusivities of different components of the multi-component bulk metallic glass Pd_(43)Cu_(27)Ni _(10)P_(20). The diffusion of the largest Pd and the smallest P was found to be drastically different. The Stokes-Einstein relation breaks down when considering the P constituent atom, while the relation is obeyed by the Pd atom over 14 orders of magnitude of change in Pd diffusivity. This difference in behavior of Pd and P poses a problem challenging for explanation. With the assist of a recent finding in metallic glasses that the β-relaxation and the diffusion of the smallest component are closely related processes by Yu [Phys. Rev. Lett. 109, 095508 (2012)10.1103/PhysRevLett.109.095508], we use the Coupling Model to explain the observed difference between P and Pd quantitatively. The same model also explains the correlation between property of the β-relaxation with fragility found in the family of (Ce _xLa_(1-x))_(68)Al_(10)Cu_(20)Co _2 with 0 ≤ x ≤ 1.