Crossover phenomena of the induced anisotropy and of the magnetic after-effect in amorphous Co58Ni10Fe5Si11B16

The existence of wide spectra of structural relaxation times in amorphous alloys has been clearly demonstrated by a series of experiments concerning the relaxation behaviour of the Curie temperature, the induced magnetic anisotropy, and magnetic or mechanical relaxation phenomena. Furthermore the simultaneous appearence of reversible and irreversible relaxation phenomena has been detected and treated theoretically on the basis of first order reaction kinetics or the so-called exhaustion kinetics. As a consequene of these spectra of relaxation times, describing reversible as well as irreversible processes, two types of crossover phenomena can be observed: 1. A reversible crossover effect can be observed if one changes the annealing temperature during an isothermal annealing run. Most clearly, the crossover phenomenon can be detected when the temperature is changed from T1 to T2 if the property previously annealed at T1 has just approached a value corresponding to the thermodynamic equilibrium value of the annealing temperature T2; 2. An irreversible crossover effect can be observed if one measures isothermal relaxation curves after different pre-treatments. In as-quenched specimens the relaxing property in general reveals a non-monotonic behaviour of the isothermal relaxation curve whereas pre-annealed specimens show a monotonic behaviour. For the same annealing temperature both isotherms, however, approach the same equilibrium value at large annealing times; So far crossover effects have been measured for the Curie temperature and Young modulus. This paper shows that the induced anisotropy or the initial susceptibility also give rise to crossover effects, thus showing that these phenomena are a characteristic property of the amorphous state as suggested previously