Does anyone know what alloys / heat treatment would be good candidates for a solenoid core that is required to have very low residual magnetism (Br), high permeability and high saturation flux density (Bm)? The form of the core will be a long thin rod. The squareness (Br/Bm) is a good indicator of residual magnetism however it is not commonly provided by manufacturers of soft magnetic alloys. I believe that some Ni-Fe alloys (which exhibit low coercive force) can achieve near zero hysteresis for bipolar DC operation if properly annealed. My goal is to find an alloy that would yield a residual magnetism of 1% or less of the saturation flux. This is to insure that when the solenoid is de-energized from a fully saturated state that there is very little residual magnetism. I suspect that the long thin form of the rod will aid in this respect as the de-magnetization factor is relatively small. Seems that some of the nickel alloys have provided this performance however I cannot locate any information to confirm the performance and annealing used.
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