High-frequency permeability of (Fe,Co,Ni)(62)Nb8B30 amorphous alloys with a wide supercooled liquid region

The increase in B content to 30 at. % for Fe-Co-Ni-Nb-B amorphous alloys ca used an extension of a supercooled liquid region before crystallization, an d a wide supercooled liquid region greater than 80 K was obtained in a wide composition range of 5-42 at. % Co and 0-10 at. % Ni for Fe62-x-yCoxNiyNb8 B30 amorphous alloys. High B-containing amorphous alloys with low Ni conten t below 10 at. % have high electrical resistivity above 230 mu Omega cm and exhibit good soft magnetic properties, i.e., a low coercive force of 2 A/m , low saturated magnetostriction of 2-7 X 10(-6), and high permeability of 21 000-29 300 at 1 kHz and 5000-7500 at 1 MHz. The high-frequency permeabil ity characteristics at 1 MHz are much better than those for any kind of sof t magnetic materials, and have been presumed to result from the decrease in eddy current loss caused by the increase in electrical resistivity. The sy nthesis of the Fe-Co-Nb-B amorphous alloys exhibiting a wide supercooled li quid region greater than 80 K and high-frequency permeability of 7500 at 1 MHz is promising for future development as a type of soft magnetic material . (C) 1999 American Institute of Physics. [S0003-6951(99)01417-5].