Collective motion of many atoms in amorphous alloys induced under passing electric current

The effects of passing a direct electric current (PEC) on the dynamic Youngʹs modulus E of a-Cu50Zr50, Cu50Ti50 and Pd50Si50 were investigated for the current density id below 4 × 103 A/cm2 using a vibrating reed technique. We observed the increases in E due to PEC, and further found that the effects of PEC on E are identical to those of applied stress on E after the scaling between id and stress. The scaling gives the effective charge number Z* which measures the electromigration force under PEC as being around the order of 105 for all the a-alloys, suggesting that the collective motion of many atoms is induced under PEC. From the changes in Z* and in the specific volume due to annealing, we evaluated the number of atoms associated with the collective motion as being several hundred.