Vacuumschmelze Gmbh

Friedrich Pfeifer

Wernfried Behnke

Gunter Klein

Willi Kessler

In order to improve the temperature constancy of induction boost in a standard working temperature range for fault current safety switches, a Ni-Mo-Cu-Fe alloy is provided whose nickel and copper content in a binary nickel-copper system is defined by a quadrangle of points A (80.5 wt. % Ni and 0 wt. % Cu), B (82 wt. % Ni and 0 wt. % Cu), C (70 wt. % Ni and 16.5 wt. % Cu) and D (70 wt. % Ni and 14.4 wt. % Cu) and whose molybdenum content, z, in wt. % satisfies the relation:

Method for producing toroidal tape cores for fault current safety

A technique for processing thin tapes of soft magnetic amorphous metal alloys to reduce their magnetic hysteresis losses. The technique involves preliminarily forming such a tape into a core, heating the core, and then controllably cooling the core, the heating and cooling being conducted in an oxidizing atmosphere. Maintaining the core during processing in a suitable longitudinal or transverse (relative to the tape) magnetic field can also produce improved properties. Certain tape cores so processed have particular magnetic hysteresis loss characteristics never heretofore known.

Reducing magnetic hysteresis losses in cores of thin tapes of soft

An alloy comprised of 45 to 53 wt. % Ni with the remainder iron, and including small amounts of deoxidizing and processing additives is worked into a 0.01 to 0.1 mm thick tape, wound to form a tape core and is then subjected to a final annealing for at least one hour at a temperature of at least 900.degree. C. and thereafter is subjected to a tempering in a magnetic cross-field (i.e., the magnetic lines of force are applied in the plane of the tape perpendicular to the rolling direction thereof). The process provides high impulse permeabilities at induction rises of 1T or larger within the so-processed tape cores. Particularly high impulse permeabilities are achieved in instances where an anisotropic structure with a privileged grain direction &lt;001&gt; in the rolling direction is generated in the tape material via heating and final deformation before winding into a tape core and via a final annealing after winding of the tape core. The so-produced tape cores are useful in various electrical applications, particularly in pulse transformers and thyristor choke coils.

Process for producing Ni-Fe magnetic tape cores

An alloy is described which contains between about 33 and 35% nickel, about 1 and 4% molybdenum and the balance iron with incidental impurities. The alloy is characterized by having a completely secondarily recrystallized structure, improved stability preventing substantial transformation to martensite at temperatures as low as -320.degree. F, high resistance and high initial permeability.

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Bruchkoebel, Germany

Friedrich Pfeifer