Fujitsu Corporation

Zenzo Henmi

Masanori Okada

Makoto Kassai

Tatsuji Sasaki

Yuichi Suzuki

Takehiko Sato

Masato Sagawa

Takeaki Sakai

Toshio Kobayashi

Etsuo Hanada

Due to an Mo addition, to a known Co-Fe-Nb semi-hard magnetic material, the coercive force is enhanced without causing deterioration of the cold workability of the semi-hard magnetic material. In addition, the energy product, the residual flux density and the fullness factor are high according to the semi-hard magnetic material of the present invention. Such material is particularly suited for reed pieces of reed switches, which are mounted in a four wire crosspoint switch.

Semi-hard magnetic material for a reed switch and process for producing

The brittle nature and magnetic properties of the rare earth cobalt magnet are improved by the simultaneous addition of Cu and V. Cu and V are included in amounts of from 0.5 to 6% by weight and from 7 to 19% by weight, respectively. The simultaneous addition enables the rear earth cobalt magnet to be cast in the form of an article. In addition, the simultaneous addition not only improves the mechanical properties of the sintered article, in which form the conventional magnet was available, but also the magnetic properties, such that, for example, the coercive force is increased when the molar ratio of cobalt with respect to rear earth elements is great.

Permanent magnet and process for producing the same

Semi-hard magnetic materials exhibiting an excellent square hysteresis loop are prepared by the following steps. An alloy material consisting essentially, by weight, of 73-93% Co, 1-5%Nb and the balance Fe is subjected to process annealing at not lower than 900.degree. C and cold working at a reduction of area of not less than 75% and then is subjected to any combination treatment involving one or more stress relief annealings at a temperature in the range 500.degree.-700.degree. C for a short period of time such that no intermetallic compound precipitates in said alloy followed by cooling to the ambient temperature, and one or more ageing treatments of said cooled material at a temperature in the range 600.degree.-900.degree. C for a considerably longer time such that an intermetallic compound does precipitate in said alloy.

Process of producing semi-hard magnetic materials

A semi-hard magnetic material characterized by a high coercive force (Hc), i.e. 20-50 Oe, can be produced by the disclosed process. In accordance with the process, an alloy consisting of 73 to 93% Co and 3 to 7% Nb, and the balance being iron is worked into a suitable form, solution treated, cold worked at a reduction of area not lower than 75% and aged. Said alloy contains niobium in a greater amount than the known alloy for the same application in order to enhance the coercive force. With the increase in the content of niobium, however, the cold workability of the alloy deteriorates. In order to overcome this disadvantage, the Inventors provide particular conditions for the solution treatment. The solution treatment consists of heating the alloy to a temperature not lower than 1000.degree.C and cooling it to room temperature. During the cooling, quenching of the alloy should be started at 800.degree.C or higher and continued to a temperature of 500.degree.C or less.

Process for producing semi-hard Co-Nb-Fl magnetic materials

A semi-hard magnetic alloy is disclosed consisting essentially of 15 to 30% of Ni, 35 to 52% of Fe, 1 to 5% of Nb and the balance cobalt. This alloy possesses a coercive force (Hc) of 10 to 50 Oe, a magnetic flux density (B.sub.100) of 10 to 17.5 KG., a squareness ratio (Br/B.sub.100) of not less than 0.70 and a fullness ratio of not less than approximately 0.70. The alloy material is also characterized by a good plastic workability.

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Kawasaki, Japan

Zenzo Henmi