Magnetische eigenschaften von ringbandkernen aus amorphen legierungen auf eisen-nickel-basis Magnetic properties of amorphous alloy toroids based on iron and nickel

Abstract

Tape wound cores of an amorphous alloy with a composition of Fe 40Ni 40P 14B 6 were stress-relieved at 325°C and subsequently cooled in a magnetic field at a well-defined rate. For an annealing treatment in a hydrogen or nitrogen atmosphere and a cooling rate of 200° C/h in a parallel field, we found a maximum permeability (dc) of 830 000, higher than for commercial permalloys. The a.c. permeability of amorphous alloy toroids is lower than for crystalline permalloys, as the eddy current losses of field-annealed toroids are rather high. A.c. values of μ 4 ∼ 40 000 and μ max ∼ 280 000 at 50 Hz for amorphous alloy toroids can be obtained, however. The losses at high frequencies are high ( P Fe = 34 W/kg at B = 0.2 T and ¢f = 20 kHz ). For the same annealing treatment in air, we found low permeability values (μ 4 ∼ 13 000) and flat hysteresis loops with a relative remanence of about 0.1. The losses at high frequencies are very low ( P Fe = 11 W/kg at B = 0.2 T and ¢f = 20 kHz ), comparable with crystalline permalloy toroids. Such a material could be used for pulse technique applications or at frequencies above 50 Hz.