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Structural relaxation in metallic glasses (MGs) occurs when the material is annealed at elevated temperatures [1], resulting in substantial property change in MGs, including diffusivity [2], plasticity [3], electrical resistivity [4], and son on. The free volume (FV) model can explain the structural relaxation in BMG. According to the FV model, structural relaxation at the elevated temperatures is resulted from a reduction of the excess free volume that was trapped in the MG during material processing [5]. A direct evidence for the free volume reduction during structural relaxation is the densification experiment performed by Haruyama [6–8]. Different models have been proposed to interpret the structural relaxation behavior, for instance, flow defect model [9-10], stretched exponential relaxation model, Šesták–Berggren SB (m, n) kinetic model, and isothermal–isoconversional method.
The relaxation of free volume has a relationship with calorimetric parameters given by,
------------------------- [1687]
where,
β -- A constant with a dimension of energy,
ΔH -- The changes in the enthalpy,
Δvf -- The average free volume during structural relaxation.
This relationship had been demonstrated experimentally by density and enthalpy relaxation measurements in a Zr55Cu30Ni5Al10 MG [11].
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[11] A. Slipenyuk, J. Eckert, Scripta Mater. 50 (2004) 39.
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