Nickel-iron alloys with special soft magnetic properties for specific applications

The magnetic properties of the initial permeability and the saturation induction characterize mainly the different available soft magnetic nickel-iron alloys. The nickel-iron alloys Magnifer 75, Magnifer 7904 and Magnifer 8105 with nickel contents between appr. 75 and 82% achieve a saturation induction of appr. 0.8 T. The initial permeability of these alloys can reach values up to a few 100,000 depending on thickness of the material and the frequency of the applied magnetic field. On the other hand, nickel-iron alloys are also available with a higher saturation up to appr. 1.6 T, but then in general with a lower initial permeability around 10,000. These are the alloys Magnifer 36 and Magnifer 50 with nickel contents of appr. 36% and 48%, respectively. In the case of Magnifer 50 different grades can be produced by different processing routes having the different grain and texture structures resulting in different magnetic behaviours. An exception is the alloy Magnifer 53 that combines both properties-high saturation induction and a relative high initial permeability-by applying a magnetic field annealing after the standard high-temperature heat treatment using tape wound cores processed from thin foil of the material. A description of the soft magnetic characteristics of nickel-iron alloys produced by ThyssenKrupp VDM GmbH and some of their applications will be presented. © 2004 Published by Elsevier B.V.