The effect of Zn, Ag and Au substitution for Cu in Finemet on the crystallization and magnetic properties

Soft magnetic ribbons of Finemet compound with Zn, Ag and Au substituted for Cu: Fe73.5Si13.5B9Nb3Cu1-xMx (M = Zn, Ag, Au; x = 0.5, 1.0) have been fabricated by rapid quenching technique with wheel speeds of 10, 25 and 30 m/s, respectively. The crystallization evolution of samples examined by DSC measurements showed that the high cooling rates make the ribbons in amorphous state whereas the samples with M = Zn; x = 0.5, 1.0 showed to be partly crystallized when they fabricated by the wheel speed of 10 m/s. In the case of Zn (x = 0.5, 1.0) and Ag (x = 1.0) substitution there is a sharp peak in the DSC curve corresponding to crystallization of alpha-Fe(Si) phase. However, the role of Au is similar to that of Cu. Hysteresis loops of as-cast samples exhibited square form which relates to the pinning centers in domain wall displacement. After appropriate annealing, the ultrasoft magnetic properties of studied ribbons are obtained. (C) 2006 Elsevier B. V. All rights reserved.