Curie temperature behaviour on annealing of Finemet type amorphous alloys

AbstractThe time–temperature dependence of Curie temperature (T C ) was determined by the DSC method for amorphousFe 73:5 Cu 1 Nb 3 Si 15:5 B 7 ribbon-shaped alloy on annealing below the crystallization temperature. Relaxation of atomicstructure of the amorphous phase on annealing was accompanied by an increase of T C . The r-shaped time dependencewas not characterized, however, by a single value of T C , since long-time annealing of amorphous samples resulted in aslow increase of T C at each temperature. The appearance of two heat capacity maxima observed after short-time an-nealing at the pre-crystallization temperature was associated with two Curie points (T C1 and T C2 ). These peaks wererelated to clustering inside the amorphous phase and to separation into two phases with different chemical composi-tions. Further annealing resulted in a-Fe nuclei appearance in the amorphous phase and consequently in the disap-pearance of iron-rich clusters. 2003 Elsevier B.V. All rights reserved.