Magnetic characteristics of a high-permeability Ni-Fe-Cu-Mo alloy

The first anisotropy constant at room temperature of a 77Ni-14Fe-5Cu -4Mo wt.% alloy has been measured; both its magnitude and its sign are shown to be dependent on the degree of short-range order in the alloy. The effect of the anisotropy on the magnetic properties of the alloy has been determined for various states of order. The highest initial permeability and the lowest coercivity occur for a vanishingly small anisotropy associated with a critical amount of order. Infinite permeability is prevented by the presence of a magnetoelastic anisotropy arising from internal stresses: the magnitude of this anisotropy can be determined.