# US 2023/0146566 A1 · Heat Treatable Magnets Having Improved Alignment Through Application Of External Magnetic Field During Binder-Assisted Molding

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- Number: US 2023/0146566 A1
- Document ID: US20230146566A1
- Status: Published application
- Kind: A1
- Application number: 17/803,661
- Filed: 2022-09-26
- Published: 2023-05-11
- Earliest claimed: 2017-11-09
- Assignees: Iowa State University Research Foundation, Inc.
- Applicants: Iowa State University Research Foundation, Inc.
- Inventors: Aaron G. Kassen; Iver E. Anderson; Emma Marie Hamilton White; Matthew J. Kramer; David J. Byrd; Liangfa Hu
- Web page: https://patentgrep.com/patent/US20230146566A1

## CPC

- H01F 1/086: {sintered}
- H01F 7/021: {Construction of PM (H01F7/0278 takes precedence; PM compositions H01F1/032)}
- H01F 41/0273: {Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003)}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

Improved manufacturing processes and resulting anisotropic permanent magnets, such as for example alnico permanent magnets, having highly controlled and aligned microstructure in the solid state are provided. A certain process embodiment involves applying a particular orientation and strength of magnetic field to loose, binder-coated magnet alloy powder particles in a compact-forming device as they are being formed into a compact in order to preferentially align the magnet alloy powder particles in the compact. The preferential alignment of the magnet alloy powder particle is locked in place in the compact by the binder after compact forming is complete. After removal from the device, the compact can be subjected to a subsequent sintering or other heat treating operation.

## Claims

### Claim at position 1

-19. (canceled)

### Claim 20

An anisotropic permanent magnet compact, comprising permanent magnet alloy particles consolidated in the presence of a binder and in the presence of a magnetic field that imparts a preferential alignment to the particles that is locked in place in the compact by the binder.

### Claim 21 (depends on 20)

The compact of claim 20 wherein the alloy particles comprise polycrystalline particles.

### Claim 22 (depends on 20)

The compact of claim 20 wherein all of the alloy particles have a diameter less than 20 microns.

### Claim 23 (depends on 20)

The compact of claim 20 wherein the alloy particles comprise AlNiCo powder.

### Claim 24 (depends on 20)

The compact of claim 20 wherein the alloy particles comprise binder-coated particles.

### Claim 25 (depends on 24)

The compact of claim 24 wherein the binder-coated particles have a polymer binder coating on the particles.

### Claim 26 (depends on 20)

The compact of claim 20 wherein the particles include an oxide coating on the individual particles beneath a particle binder coating.

### Claim 27 (depends on 20)

The compact of claim 20 wherein the alloy particles comprise, in weight. %, about 7 to about 8% Al, about 13 to about 15% Ni, about 24 to about 42% Co, up to about 3% Cu, up to about 8% Ti, and balance Fe and incidental impurities.

### Claim 28 (depends on 27)

The method of claim 27 wherein the alloy particles comprises, in weight.%, 7.1% Al, 13.0% Ni, 40.1% Co, up to 3.0% Cu, up to 6.5% Ti, up to 0.5% Nb, and balance substantially Fe and incidental impurities.

### Claim 29 (depends on 20)

An anisotropic permanent magnet comprising the compact of claim 20 that has been heat treated to achieve grain growth in a direction of the preferential alignment within at least a portion of the volume of compact.

### Claim 30 (depends on 29)

The magnet of claim 29 which has been thermally debinded and sintered in a single phase high temperature region of the magnet alloy for a time to produce grain growth

### Claim 31 (depends on 30)

The magnet of claim 30 that has a single crystal microstructure or a microstructure having enlarged grains having a millimeter-sized grain dimension in a grain growth direction.