DE1235599B - Process for the production of magnetically and crystallographically anisotropic sintered permanent magnets - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C22c

German KL: 40 b -33/02

Number: 1235 599

File number: M 52884 VI a / 40 b

Filing date: September 1, 1960

Open date: March 2, 1967

It is known to manufacture magnets from alloys which, in addition to iron, essentially contain cobalt (15th century) up to 30%), nickel (11.5 to 20%) and aluminum (6 to 11 "/ o) contain (Alnico magnets). In addition to these elements and impurities, Ti (0 to 6%), Cu (0 to 7%), V, Nb may also be included together, individually or in combinations. These magnets can be roughly divided into four large groups: ■ ;, ·.

a) AlnicprMagnete, their magnetic properties are the same in all spatial directions (isotropic Alnipo magnets), the one magnetic Goodness of about '

reach;

b) Alnico magnets, in which a spatial direction through a suitable heat treatment in the magnetic field is magnetically excellent (anisotropic alnico magnets); with them one achieves magnetic quality values up to about

measured in the marked direction (preferred direction);

c) Alnico magnets, which initially receive a crystallographic preferred direction, so that the predominant part of the existing crystallites each with one of their [100] directions is parallel (Stem crystallization) and then followed by a heat treatment in a magnetic field where the magnetic and crystallographic preferred directions coincide. Here values of the magnetic quality can be up to

to be achieved;

d) Alnico magnets, which consist of a single crystal and in which the preferred magnetic direction is parallel to a [100] direction of the crystal lies. Magnetic quality values of

12 106 G Oe

have been measured on such crystals.

Group a, b and c magnets are already being produced technically in large quantities; those of group d are so far only on a laboratory scale under special precautionary measures from the Melt pulled.

Method of manufacture magnetic and
KristaUographically anisotropic
sintered permanent magnets

Applicant:

Magnet factory Bonn G. mb H.,
vorm. Windhorst union,
Bonn, Dorotheenstr. 215

Named as inventor:

Dr. Günther Heimke, Buschdorf;

Dr. Erich Steingroever, Bonn

Magnets of groups a and b are produced both by casting and sintering. Belonging to group c Up to now, magnets have mostly been made by casting, because of the column crystallization in magnets this group by generating as strong a temperature gradient as possible during solidification must be forced from the melt.

It has also been proposed to produce such magnets by sintering in a magnetic field or by that a seed crystal is inserted into the compact, the crystal axis of which is in the desired position Direction of magnetization and which should determine the crystal growth of the whole magnet. That Sintering in a magnetic field is hardly feasible in practice, because work must always be carried out in a vacuum or under protective gas and the facilities for simultaneous generation of the vacuum or protective gas, the magnetic field and that required for sintering high temperatures interfere with each other extraordinarily; the other suggestion, one Inserting a seed crystal into the pressed part is not possible when producing larger quantities of magnets perform and also unreliable because at the points of the pressed part that are further away from the germ are, crystals spontaneously begin to grow with undesired axis directions.

In the method according to this invention, the columnar crystallization is carried out on Alnico magnets which are placed on are manufactured using sintering technology, produced in a novel and also reliable way.

This preferred crystallographic direction can be enforced by the measure described below will:

709517/436

Claims (2)

Several mixtures of the metal powders are produced, which differ in the content of one of the powders of the essential alloy metals. The concentrations of the mixtures in the selected alloy metal should not deviate too far from the magnetically optimal composition. Is the concentration of cobalt for the achievement of magnetically high quality body z. B. at 24 ° / oj so you can produce powder mixtures with 20, 21, 22, 23, 24, 25, 26, 27, 28 * / oCo. These powder mixtures are introduced into the mold one after the other, so that a uniform concentration gradient is created. Expediently, after each individual mixture has been introduced, it is fixed with one fiftieth to one tenth of the usual pressure before the mixture with the adjacent concentration is layered over it. Finally, it is then pressed again with the pressure customary in the production of such sintered bodies. The further processing of these sintered bodies with a concentration gradient of zo takes place in a manner known per se. During the heat treatment, the magnetic field is again parallel to the stem axis. In the example carried out, magnetic quality values of 7.6 -106G-Oe were found in the preferred direction, as The method described above also allows the production of a curved columnar crystallization. Here, the concentration gradient must have a curvature corresponding to the intended curvature of the stem axes. Patent claims: 1. Process for the production of sintered, magnetically anisotropic permanent magnets from a Alloy of iron with essentially cobalt, nickel and aluminum that are parallel to the direction the preferred magnetic layer contain a preferred crystallographic direction, thereby characterized in that the compact is built up from several layers, the metal powder mixture of which is gradually increased in concentration one of the alloying elements cobalt, nickel or aluminum differentiates in such a way that there is a concentration gradient in the compact with respect to the selected alloying element arises, with an average concentration corresponding to the composition known per se, which is sintered and heat-treated in a known manner. 2. A process for the preparation of sintered permanent magnets according to claim 1, characterized in that a curved crystallographic (and magnetic) preferential direction is generated within the magnet by the concentration gradient receives a desired curvature of the preferred position corresponding curvature Considered publications:
German Patent No. 877,318;
French patent specification No. 1 018 451. 709 517/436 2.67 © Bundesdruckerei Berlin