US2347543A

US2347543A - Alloy for permanent magnets

Info

Publication number: US2347543A
Application number: US171214A
Authority: US
Inventors: Dannohl Walter; Neumann Hans
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-01-07
Filing date: 1937-10-27
Publication date: 1944-04-25
Anticipated expiration: 1961-04-25

Description

Patented Apr. 25, 1944 2,347,543 ALLOY FOR PERMANENT MAGNETS Walter Siemensstadt, Property Custodian Dannohl and Hans Neumann, Berlin- Germany; vested in the Alien No Drawing. Application October 27, 1937, Serial No. 171,214. In Germany January 7, 1937 Claims.

Our invention relates to an alloy for permanent magnets.

It is known to employ as material for the manufacture of permanent magnets alloys of cobalt, nickel and copper and alloys of irons, nickel and copper. The just-mentioned magnets of cobalt, nickel and copper are described in our U. S. Patent No. 2,170,047, granted August 22, 1939, on our copending application Serial No. 111,252, filed November 1'7, 1936, of which this is a continuation-in-part. These magnets have excellent magnetic qualities such as a potential coercive force above 100 oersted together with the advantage of being machineable by cutting tools and having a higher mechanical strength than other high grade magnets.

According to the present invention, similar advantages are obtained by employing alloys of cobalt, nickel, copper and iron for producing permanent magnets. Magnets of this composition have considerably better magnetic properties than the known iron-nickel-copper alloys, and are advantageous even in comparison with ternary nickel-cobalt-copper alloys, since by virtue of the iron content they may have a cheaper composition and also present improved working properties.

v Magnets according to our present invention contain 1 to 35% iron, to 45% nickel, 1 to 70% cobalt, and to 80% copper.

Alloys containing 5 to iron, 15 to nickel, 5 to cobalt and 30 to 60% copper show especially favorable magnetic properties. The magnetic properties of magnets according to the invention are further enhan ed if the alloys are first heated above 1000 C.,"

500 and 750 C.

The improvement of the magnetic properties attained by alloys according to the invention will become apparent from the following table referring to a number of examples of different composition.

In the first column or this table are indicated then quenched and finally reheated to a temperature between the alloys of which those designated by a refer to iron-nickel-copper, whereas the alloys band 0 are obtained from the alloys a by substituting cobalt for a portion of iron. The last three columns of the table indicate the values of the remanence, the coercive force and the magnetic power Br.JHc Particularly noteworthy is the great increase of the coercive force present in every case. Thus, for instance, with an alloy containing 40% iron, 20% nickel and 40% copper, the coercive force increases from 30 to 240 oersted if cobalt is substituted for 30% iron. At the same time also the remanence increases by 10% from 5,100 to 5,600 gauss. The improvement is also apparent from the increase in the magnetic power Bib-7H0 from 1.5.10 to 12.6.10.

In some cases, such as in examples 1b and 2b, the substitution of cobalt for iron effects not only an increase in the coercive force, but also an increase in the remanence. In other cases, such as in alloy 5b, the-remanence is not affected, and in some cases a decrease of the remanence is noticeable, as will be seen from alloys 4b and 6!: showing a 'decrease of approximately 10%. In the last-mentioned case, the coercive force is considerably increased so that the product of these two magnitudes shows a considerable improvement of the magnetic properties as compared to the known iron-nickel-copper alloys.

The alloys designated by a were produced with the most favorable heat treatment in order to attain the best possible magnetic properties. The alloys designated by b and 0 were produced in such a manner that the material was at first heated for 10 hours at a temperature of 1,050 and 1,100 centigrade respectively, then quenched in oil, annealed for 1 to 40 hours at a temperature of 600 to 700 centigrade and finally cooled down to room temperature. The fluctuations in the annealing period are found necessary, since different compositions required different periods for obtaining the best magnetical properties. For other compositions than given in the table, departures from these periods and temperatures may appear appropriate.

The alloys may contain small amounts of reducing materials, for instance, about 1% man- 'ganese, small quantities of silicon, magnesium,

aluminum or beryllium, or several of such common additions.

What is claimed is:

1. A permanent magnet formed of an alloy containing 5 to 25% iron, 15 to 35% nickel, 5 to 40% cobalt, and a balance consisting substantially of 30 to 60% copper, besides minor amounts of customary additions and impurities, and being magnetized up to a coercive force above oersted and a remanence above 1,000 gauss;

2. A permanent magnet formed of an alloy and being magnetized to a magnetic power above 10.

5. A permanent magnet formed of an alloy containing 1 to iron,

10 to nickel, 5 to cobalt and a balance of 20 to consisting substantially of copper, and exhibiting a magnetic power above 10 upon quenching from above 1000 C. and tempering between 500 and WALTER. DANN6HL. HANS NEUMANN.