Ring magnetic cores made from nickel-iron-molybdenum alloy tape - where tempering in magnetic field produces optimum combination of permeability and remanence

摘要

The tape contains by wt. 76-82% Ni, 3-6 Mo, 0-6% Cu, remainder Fe with small amts. of deoxidants; and the cores have a high permeability with a.c. or pulsed d.c. The tape is wound into a ring core, which is annealed in dry hydrogen at 1050-1250 deg.C. The core is then immediately tempered for 1-10 hrs. at 300-400 deg.C. in a magnetic field, in which the field lines are at 90 deg. w.r.t. the subsequent direction of the magnetic flux in the core. The magnetic field tempering is pref. at 350-380 deg.C., and is esp. for 3-4 hrs. at 370 deg.C. Used esp. in protective switches detecting leakage- or faulty- currents. A uniformly high permeability is obtd. with a.c. or pulsed d.c.