Abstract
This paper reports dc and ac magnetic properties of amorphous Fe40Ni38‐Mo4B18 (METGLAS : 2826MB) annealed at various temperatures. DC coercive force showed minimum and squareness ratio reached almost unity annealed at about 350 °C, however, ac permeability turned out extremely low. High permeability has been obtained by annealing above 400 °C at the cost of increase of dc coercive force and decrease of squareness ratio. Nonlinear and hysteretic changes of permeability against ac magnetic field have been observed in materials annealed below 380 °C and as‐quenched materials. These defects have been overcome by annealing above 400 °C. Disaccommodations, which are very large in materials annealed below 380 °C, have disappeared also when annealed above 400 °C.