Determination of the attempt frequency for relaxation phenomena in amorphous metals

Abstract

It is well known that amorphous alloys show structural relaxation behaviour during annealing and that this can be described by the AES model [1]. One important parameter, used in the AES model, is the attempt frequency. It will be shown that a good knowledge of the latter is of vital importance to describe the relaxation behaviour of an amorphous alloy in a quantitative way. Therefore, the attempt frequency for relaxation phenomena in an amorphous Fe40Ni40B20 alloy was determined. In this paper we present a set of high resolution d.c. electrical resistance measurements performed during annealing of Fe40Ni40B20 amorphous ribbons. We calculated the attempt frequency by using a linear regression technique, and found a value of v0 = 8.0 x 10(13) Hz. There is good agreement with the results found by Gibbs [2], who analysed the experimental data of Mulder et al. [3], who used a pulse echo technique to measure the change of Young's modulus of Fe40Ni40B20 amorphous ribbons during relaxation. Also, it is clear that the attempt frequency is of the order of the Debye frequency. This suggests [1] that the observed relaxation involves rather single atom processes instead of the cooperative motion of large groups of atoms.