Relaxation effects in the Moessbauer hyperfine structure of amorphous Fe70Co10B20 at 125deg C

A new approach was attempted in following the irreversible relaxation effects in the hyperfine structure of amorphous Fe70Co10B20. Room temperature transmission 57Fe Moessbauer spectra were measured in the course of interrupted isothermal annealing. For the data fitting, a model of pseudo-three-dimensional distribution of correlated hyperfine parameters was adopted and the corresponding spectrum modelled by a FFT-based procedure. In addition to commonly used hyperfine parameters, the second order quadrupole splitting was also considered. The time dependences of the average magnetic and the second order quadrupole splittings show two relaxation stages interpreted as the relief of quenched-in stresses and the free volume shrinking. (orig.)