The mechanical relaxations of a Mm₅₅Al₂₅ Ni₁₀Cu₁₀ amorphous alloy studied by dynamic mechanical analysis

The mechanical relaxation behaviors of a misch-metal (Mm)-based amorphous alloy, Mm₅₅Al₂₅Ni₁₀Cu₁₀, were studied by using the time-temperature superposition (TTS) principle. From the results of isothermal multi-frequency dynamic mechanical measurements, the master curves for elastic moduli (storage and loss moduli) and loss factor (tan δ) were constructed. The temperature dependence of the shift factor was found to follow the Arrhenius relationship at two temperature regions, below and above T_g, and the activation energies calculated from the relationship were about 78 and 323 kJ/mol which are associated with the low temperature relaxation and viscous flow, respectively. The decoupling of low temperature and viscoelastic relaxations, shown in the temperature dependence of the shift factor, manifests the glass transition region of this alloy and compared with the results of the calorimetric measurements. From the temperature dependence of the shift factor, the fragility index of this alloy was estimated.