Johari–Goldstein relaxation as the origin of the excess wing observed in metallic glasses

An explanation of the differences in diffusivity of the components of the metallic glass Pd43Cu27Ni10P20

“…(1) and (2) related. Experiments carried out in many different kinds of glass-formers [7] including metallic glasses [5] have shown the relaxation time, τ β , of the β-relaxation can be identified with the primitive relaxation time τ 0 . On combining these two properties, the temperature dependence of the diffusion coefficient of P, D P , can be identified with that of the primitive relaxation time τ 0µ appearing in Eq.(2).…”

“…It is either resolved in the isochronal mechanical loss spectra [1-31-3], or presented as an excess wing on the high frequency (low temperature) side of the isothermal (isochronal) spectra [4,5]. There is only one secondary relaxation present in BMG.…”

“…property (5), that the diffusion motion of the smallest constituting atom of BMG and the β-relaxation are related, and they have the same activation energies in the glassy state.…”

βrelaxation and low-temperature aging in a Au-based bulk metallic glass: From elastic properties to atomic-scale structure

“…More recently, there have been many reports of observations of a slow β (or Johari-Goldstein [16]) relaxation 1 in BMGs commonly characterized by a peak in the loss modulus versus temperature curve measured using dynamic mechanical analysis (DMA) at a constant heating rate [17][18][19][20][21][22][23][24]. The observed peak temperature depends on the test frequency, increasing at higher frequencies, and hence the peak can often overlap with the dynamic α-relaxation peak, appearing as an excess wing or inflection, and may approach the dynamic T g at MHz frequencies [17][18][19][20][21][22][23][24].…”

“…The observed peak temperature depends on the test frequency, increasing at higher frequencies, and hence the peak can often overlap with the dynamic α-relaxation peak, appearing as an excess wing or inflection, and may approach the dynamic T g at MHz frequencies [17][18][19][20][21][22][23][24]. By considering a heterogeneous model of BMG atomic structure with both higher free volume soft regions and denser hard regions, it has been suggested that atomic rearrangements during the slow β relaxation occur in the soft, higher free volume regions [25,26].…”