US2264038A - Permanent magnet containing titanium - Google Patents

Description

5680 and a BHmax. of 1,800,000.

Patented Nov. 25, 1941 PERMANENT MAGNET CONTAINING TITANIUM Goodwin H. Howe, Scotia, N. Y., assignor to General Electric Company,

a corporation of New York No Drawing. Application June 14, 1940, Serial No. 340,565

Claims. (01. 148-3) The present invention relates to permanent magnets and particularly to permanent magnets which contain a relatively large quantity of titanium. Permanent magnet compositions containing such a quantity. of titanium have been disclosed in various patents and various methods have been suggested for fabricating such alloys. Heretofore, however, such permanent magnets have never been produced commercially due to difiiculty in obtaining sound castings and to the 1 fact that such cast material did not possess magnetic properties equal to the properties of alnico magnets of the type disclosed in Ruder Patents 1,947,274 and 1,968,569.

It is one of the objects of the present invention to provide a permanent magnet containing a relatively large quantity of titanium which magnet may be manufactured easily and which has high permanent magnet properties.

The alloy which I employ contains iron, nickel,

aluminum, cobalt and titanium as the essential ingredients. A composition of this character is disclosed in British Patent 476,702. However, the process which I have found it necessary to employ in order to obtain satisfactory permanent magnet properties differs from that disclosed in the British patent. I

In carrying out my invention the iron, nickel and cobalt ingredients are melted together preferably in a high frequency furnace. Thereafter the desired quantities of aluminum and titanium are added generally in the order indicated. After the ingredients have been melted, the molten alloy 'is cast in core sand molds. To obtain the best results the molten alloy should be poured 35.

very hot and the casting stripped from the mold as quickly as possible, for example when. the sprues are hardly set. Stripping the casting from the mold in this manner is necessary for the residual of 5650, a coercive force of 900 anda BHmax. of 1,650,000.

For best results the alloy should be cooled to room temperature after it has been cast, and thereafter given a draw as above indicated. If the alloy after casting and during cooling, or at any other time, is held at temperatures above 1000 C. or even at temperatures above 700 C., particularly the former, the permanent magnet properties of the alloy are adversely affected. .On the other hand, if the alloy on cooling from casting is held at a temperature of about 600 C. for five hours fair results may be obtained,

- for example, a residual of 5550, a coercive of 910 and a BHmax. Of 1,500,000.

While some variation in the percentage ingredients of the alloy is permissible the ingredients and percentages thereof which provide sound castings having high permanent magnetic properties arethose ingredients and percentages recited in applicants specification and claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The method of making an alloy containing 30 to 36% cobalt, 16to 25% nickel, 6 to 12% titanium, an aluminum content equal to about 60 to 80% of titanium content with the remainder substantially of iron which comprises meltingthe allow ingredients, pouring the molten alloy into a mold, stripping the casting from. the mold as soon as it has solidified, air cooling to room temperature and thereafter drawing for a production of castings having the most desirable magnetic; characteristics. The cast alloy is permitted to cool in air to room temperature and thereafter is drawn for about five hours at a temperature of about 650 C. after which the alloy preferably is slowly cooled, for example cooled in the furnace to a temperature of about 300 0. V i

An alloy consisting of about 18% nickel, 8%

titanium, 35% cobalt, 6% aluminum with the remainder iron, except for incidental impurities, when produced in accordance with the above process had a coercive force of 1053, a residual of Drawing the few hours at a temperature of about 600 to 2. The method of making an alloy containing 30 to 36% cobalt, 16 to 25% nickel, 6 to 12% titanium, an aluminum content equal to about to of the titanium content with the remaindersubstantially of iron which comprises melting the alloy ingredients, pouring the molten alloy into a mold, stripping the casting from the mold as'soon as it has solidified, air cooling to room temperature and thereafter drawing for a few hours at a temperature of about 650 C.

3. The method of making an alloy containing 30 to 36% cobalt, 16 to 25% nickel, 6 to 12% titanium, an aluminum-content equal to about '60 r5809; ofthe titaniumcontent with the remold as soon as it has solidified, air cooling to alloy for five hours at about 550 C. resulted in a 55 room temperature and thereafter drawing for five hours at a temperature of about 650 C.

4. The method of making an alloy containing 2 Y 30 to 36% cobalt, 16 to 25% nickel, 6 to 12% titanium, an aluminum content equal to about 60 to 80% of the titanium content with the remainder substantially of iron which comprises melting the alloy ingredients, pouring the molten alloy into a mold, stripping the casting from the 5. The method of making an alloy containing about 18% nickel, about 8% titanium, about 3 5% cobalt, about 6% aluminum, with the remainder iron excepting for incidental impurities which comprises melting the alloy ingredients, pouring the molten alloy into a mold, stripping the casting from the mold as soon as it has solidifled,.air cooling the casting to room temperature and thereafter drawing it for a few hours ata tem- 10 'perature of 600 to 650 C.

GOODWIN H. HOWE.