Magnetic properties, aging effects and application potential for magnetic heads of Co‐Fe‐Si‐B amorphous alloys

Zero magnetostrictive alloys (Co0.94Fe0.06)‐Si‐B about 5mm wide and ∼25 μm thick were prepared by the single roller type quenching method. By choosing proper compositions and by annealing at temperatures higher than the Curie temperature, the alloys with saturation magnetic flux density of 0.95 T in which permeabilities are as high as 500 at 5 MHz, were obtained. The permeabilities at frequenceis below about 100 kHz decrease drastically even by aging at temperatures as low as 100°C. At high frequencies above about 500 kHz, no significant changes occur in the permeabilities by similar aging. Therefore, the alloys are suitable for high frequency applications. Recording and reproducing characteristics of a video head made of the amorphous alloy were measured at frequencies from 1 to 6 MHz, using Co‐γ‐Fe2O3 magnetic tapes. The output signals for the head are higher than those for both Mn‐Zn ferrite heads and Sendust alloy heads.