Study of internal friction behavior in a Zr base bulk amorphous alloy around the glass transition

In the present work, mechanical spectroscopy measurements have been performed over broad frequency and temperature regions on a bulk Zr55Cu25Ni5Al10Nb5 amorphous alloy. This alloy shows a distinct calorimetric glass transition and a high thermal stability with respect to crystallization. Dynamic mechanical analysis clearly demonstrates a main relaxation related to the glass transition, Tg. Frequency dependence of internal friction at temperatures in the vicinity of the glass transition temperature can be well described using a physical model, which can characterize the mechanical response of disordered condensed materials and especially the characteristic main relaxation time τmol. As a consequence, activation parameters for the dynamic glass transition of the amorphous alloy are determined through isothermal measurements of internal friction. Furthermore, the temperature dependence of the characteristic relaxation time is theoretically confirmed. There is also a good agreement between the well-known fragility parameter, m, and the parameter a of the physical model which characterizes the degree of deviation from the Arrhenius law of the τmol.