Fe-Si-Al-Ni系新高透磁率合金“Super Sendust”の磁気特性におよぼすNi含有量の影響

Abstract

The crystal magnetic anisotropy constant Kc and the magnetostriction λs of a Sendust alloy in composition of 9.6%Si-5.4%Al-bal.Fe are almost equal to zero. Therefore this alloy shows high permeability, but its brittleness makes the alloy to be hardly rolled. With the object of developing a new alloy having higher permeability and workability, we have made a study of effects of the addition of Ni as a fourth element on magnetic properties of 6%Si-4%Al-bal.Fe alloy showing a second largest value of maximum permeability μm in the Fe-Si-Al system. In this paper the dependence of magnetic properties of 6%Si-4%Al-bal.Fe alloy containing 0 to 7%Ni on annealing conditions and the effects of magnetic field treatment are described in detail. The experimental results obtained are summarized as follows:(1) Magnetic properties of the 6%Si-4%Al-bal.Fe alloy are remarkably influenced by Ni addition, especially by the addition of 2∼4%Ni the coercive force Hc decreases and then the maximum permeability μm increases considerably.(2) An alloy in composition of 3.15%Ni-5.33%Si-4.22%Al-bal.Fe was heat-treated under the optimum conditions, that is, annealing at 750°C for 1 hr in hydrogen and cooling to room temperature at a rate of 1.7°C/sec, and the following magnetic properties were obtained: μm=56800, Hc=0.096 Oe, Br=8100 G, Bm=9800 G and Kf=86.6%.(3) Magnetic properties of the above-mentioned alloy are improved strikingly by heattreatment in a magnetic field. When applying a magnetic field 20 Oe during cooling from 700°C to room temperature after annealing at 1250°C for 1 hr in hydrogen, the following magnetic properties were obtained: μm=165000, Hc=0.03 Oe, Br=9540 G, Bm=10900 G and Kf=87.5%. Therefore, we have named this newly detected high permeability alloy “Super Sendust”.(4) The values of magnetostriction λs, magnetic moment σs, Curie point Tθ, electrical resistivity ρ and Vickers hardness Hv of the new alloy were affected considerably in the composition range of 2 to 4%Ni.