Method of producing a strip of nanocrystalline material and device for producing a wound core from said strip

Abstract

The invention relates to a method of producing a strip of nanocrystalline material which is obtained from a wound ribbon that is cast in an amorphous state, having atomic composition [FeCoNi]CuSiBNbM'M″, M′ being at least one of elements V, Cr, Al and Zn, and M″ being at least one of elements C, Ge, P, Ga, Sb, In and Be, with: a ≦0.07 and b ≦0.1, 0.5 ≦x ≦1.5 and 2 ≦α≦5, 10≦y≦16.9 and 5≦z≦8, β≦2 and γ≦2. According to the invention, the amorphous ribbon is subjected to crystallization annealing, in which the ribbon undergoes annealing in the unwound state, passing through at least two S-shaped blocks under voltage along an essentially longitudinal axial direction of the ribbon, such that the ribbon is maintained at an annealing temperature of between 530° C. and 700° C. for between 5 and 120 seconds and under axial tensile stress of between 2 and 1000 MPa. The tensile stress applied to the amorphous ribbon, the displacement speed of the ribbon during annealing and the annealing time and temperature are all selected such that the cross-section profile of the strip is not in the form of a Ω and the maximum deflection of the cross-section of the strip is less than 3% of the width of the strip and preferably less than 1% of the width. The invention also relates to the strip and the core thus obtained and to the device used to implement said method.