Nickel-lron-Based Alloys

The fee phase in the Ni—Fe alloy system and the formation of the ordered Ni3Fe phase provide a wide range of structural and magnetic properties for developing soft magnetic materials with specific characteristics for different applications. The phase diagram is shown in Sect. 3.1.5. Before amorphous and nanocrystalline soft magnetic alloys were introduced, the Ni—Fe materials 

The main fields of application of high permeability Ni—Fe alloys are fault-current circuit breakers, LF and HF transformers, chokes, magnetic shielding, and high sensitivity relays. 

It should be noted that annealing treatments in a magnetic field of specified direction induce atomic rearrangements which provide an additional anisotropy termed uniaxial anisotropy TTu. It can be used to modify the field dependence of magnetic induction in such a way that the hysteresis loop takes drastically different forms, as shown in Fig. 4.3-13. 

Combined with small alloy variations, primary treatments and field annealing treatments, a wide variety of annealed states can be realized to vary the induction behavior. The field dependence of the permeability of some high-permeability Ni—Fe alloys (designations according to Vacuumschmelze GmbH) are shown in Fig. 4.3-14 [3.16], 

Alloys of Ni—Fe in the range of 54-68 wt% Ni combine relatively high permeability with high saturation 

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