The effect of induced transverse magnetic anisotropy in Finemet-type nanocrystalline alloys modified by Co on their magnetic properties and power losses

摘要

The process of inducing transverse magnetic anisotropy in toroidal cores was investigated. Ribbon amorphousness was determined by the XRD method. Thermo-magnetic treatment was used to induce transverse magnetic anisotropy. The (Fe_(1-x)CO_x)_(73.5)Cu_1Nb_3Si_(13.5)B_9 cores containing various amounts of Co (from x = 0 to 0.8) were subjected to heat treatment conducted at different temperatures T_a(763 - 823K) in an external magnetic field of 24 to 160 kA/m, perpendicular to the ribbon casting direction. The effect of the chemical composition, annealing temperature and magnetic field intensity on the induced transverse magnetic anisotropy was examined. Dynamic magnetic parameters of the cores (mu,P_S) were measured at the magnetizing field frequency ranging from 50 Hz to 50 kHz. The nanocrystalline cores made from the (Fe_(1-x)Co_x)_(73.5)Cu_1Nb_3Si_(13.5)B_9 ribbons (X = 0.54; 0.8) were applied in a transformer for the 230 V_(AC)/48 VDC rectifier, 400 W in power. The laboratory tests confirmed correct operation of these cores at the temperature of 473 K. It was also found that application of nanocrystalline cores enabled significant reduction of the transformer dimensions.