Elasticity study on collective motion in metallic glasses

The frequency dependence and the strain amplitude dependence of the dynamic Young's modulus in amorphous (a-) Cu50Ti50, a-Zr50Cu50 and a-Zr55Cu30Al10Ni5 were investigated at room temperature by means of the vibrating reed method. In the following, f and ɛ denote the frequency and the strain amplitude, respectively. The frequency dependence of the dynamic Young's modulus was measured at ɛ∼10−6 in the frequency range between 101 and 104Hz, where a strong decrease in the dynamic Young's modulus between 101 and 104Hz was found. The strain amplitude dependence of the dynamic Young's modulus was measured at f∼102Hz in the strain amplitude range between 10−5 and 10−3, where a strong increase in the dynamic Young's modulus with increasing strain amplitude was found. The effect of passing an electric direct-current on the dynamic Young's modulus at ɛ∼10−6 and f∼102Hz was also investigated, where a net increase in the dynamic Young's modulus with increasing current density in the range of 107A/m2 was found. These results were discussed from the point of view of the resonant collective motions of many atoms in metallic glasses.