COMPARISON OF THE THERMOMAGNETIC AND THERMAL EFFECTS DURING NANOCRYSTALLIZATION OF AMORPHOUS FE76.5-XCU1NBXSI13.5B9 ALLOYS

The results of thermomagnetic (TM) and calorimetric (DSC) measurements have been compared in order to clarify some details of the mechanism of nanophase-formation from Finemet-type precursors with different Nb contents. It was found that the main features of the DSC thermograms ( shape, relative separation and amplitude of the exothermic peaks chara cteristic for the precipitation of the Fe-(Si) solid solution and the transition metal borides) depend mainly on the composition of the prec ursor glass, and are only slightly affected by the heating rate betwee n 20 and 80 K/min. The amplitude of the uprise of the magnetization in the TM curves (attributed to the precipitation of bcc-Fe(Si) and bori des) decreases with increasing Nb-content. The Curie-temperature of th e precursor glasses, T-c(am(1)), the remainder amorphous phases, T-c(a m(2)) and the bcc nanophase, T-c(n-Fe) are determined from the thermom agnetic curves. The shape of the TM curves is interpreted on the basis of the reactions describing the crystallization of the hypo-eutectic Fe-B glasses.