Effect of the Si/B ratio on the magnetic anisotropy distribution of Fe73.5Si22.5-xBxCu1Nb3 (x = 7, 9, 16) alloys along nanocrystallization

The effect of the Si/B ratio on the magnetic anisotropy distribution of Fe7 3.5Si22.5-xBxCu1Nb3 (x=7,9,16) alloys has been studied. The influence of is ochronal annealing on the hysteresis loop of the three studied alloys has b een analyzed. They present two minima in coercivity: the first one can be a scribed to structural relaxation, and the second one is related to the aver aging of the magnetocrystalline anisotropy, as predicted by the random anis otropy model. The relative importance of both minima changes with Si conten t: the lower the Si content, the more effective the structural relaxation a nd the less important the second minimum are. The mean value of the magneti c anisotropy distribution presents a similar behavior, evidencing the growi ng importance of the magnetoelastic anisotropy for the relaxed amorphous sa mples as the Si content is increased. From the evolution of the magnetic an isotropy distribution along nanocrystallization and the microstructural inf ormation obtained from transmission electron microscopy images, the behavio r of the coercivity minima with changes in Si content can be ascribed to a different degree in compensation of magnetoelastic anisotropy due to the co ntributions of different signs coming from the nanocrystals and the amorpho us matrix. (C) 1998 American Institute of Physics. [S0021-8979(98)04820-8].