Reversible and Irreversible Length Changes in Amorphous Fe sub 40 Ni sub 40 B sub 20 During Structural Relaxation

Measurements are presented of the isothermal and isochronal change of length during structural relaxation of amorphous Fe sub 40 Ni sub 40 B sub 20 . The observed changes in length can be separated in three contributions: an irreversible part with a well defined activation energy of 250 kJ/mol, which is well described by the free volume model; a relatively small reversible part in the activation energy range from 210-250 kJ/mol and with a magnitude of approx 0.4 ppm/K. This is ascribed to chemical short range ordering; an irreversible part in the activation energy range from 130-250 kJ/mol, with a magnitude of approx 800 ppm in as-quenched specimens. It is shown that the length isothermals of as-quenched specimens, after correction for the free volume contribution, can be scaled to form a "masterplot". 14 ref.--AA