# US 11,441,218 B2 · MnAl alloy and production method thereof

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- Number: US 11,441,218 B2
- Document ID: US11441218B2
- Status: Granted
- Kind: B2
- Application number: 16/475,439
- Filed: 2017-12-27
- Published: 2019-11-07
- Granted: 2022-09-13
- Earliest claimed: 2017-01-05
- Assignees: TDK Corporation
- Applicants: TDK Corporation
- Inventors: Suguru Satoh; Shuichiro Irie; Yasunao Miura
- Web page: https://patentgrep.com/patent/US11441218B2

## CPC

- C22F 1/16: of other metals or alloys based thereon
- B22F 1/142: Thermal or thermo-mechanical treatment
- B22F 9/14: using electric discharge
- C22C 21/00: Alloys based on aluminium
- C22C 22/00: Alloys based on manganese
- C22F 1/04: of aluminium or alloys based thereon
- H01F 1/147: Alloys characterised by their composition {(treatment thereof for enhancing their electromagnetic properties C21D8/12)}
- B22F 9/04: starting from solid material, e.g. by crushing, grinding or milling ({C22C1/1084 takes precedence}; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C)
- B22F 2009/041: {by mechanical alloying, e.g. blending, milling}
- B22F 2009/049: {by pulverising at particular temperature}
- B22F 2301/052: Aluminium
- B22F 2998/10: Processes characterised by the sequence of their steps
- C22C 2202/02: Magnetic
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

An object of the present invention is to provide a Mn-based alloy exhibiting metamagnetism over a wide temperature range. A Mn-based alloy according to the present invention is a MnAl alloy having metamagnetism. The metamagnetism refers to a property in which magnetism undergoes transition from paramagnetism or antiferromagnetism to ferromagnetism by a magnetic field. In the MnAl alloy, an antiferromagnetic state is adequately stable, so that by imparting AFM-FM transition type metamagnetism (the type of metamagnetism undergoing transition from antiferromagnetism to ferromagnetism), it is possible to obtain metamagnetism over a wide temperature range, particularly, over a temperature range of −100° C. to 200° C.

## Claims

### Claim 1

A MnAl alloy exhibiting metamagnetism,
wherein a composition of the MnAl alloy is expressed by MnbAl100-b and 45≤b≤50,
wherein the MnAl alloy contains crystal grains having a τ-MnAl phase, and
wherein a composition of the τ-MnAl phase is expressed by MnaAl100-a and 48≤a≤55.

### Claim 2 (depends on 1)

The MnAl alloy as claimed in claim 1,
wherein a magnetic structure of the τ-MnAl phase has an antiferromagnetic structure in a non-magnetic field state.

### Claim 3 (depends on 2)

The MnAl alloy as claimed in claim 2, wherein the composition of the τ-MnAl phase is expressed by MnaAl100-a and 50<a<55.

### Claim 4 (depends on 1)

The MnAl alloy as claimed in claim 1, wherein an order parameter of the τ-MnAl phase is 0.85 or more.

### Claim 5 (depends on 1)

The MnAl alloy as claimed in claim 1, wherein the MnAl alloy exhibits the metamagnetism over a temperature range of −100° C. to 200° C.

### Claim 6 (depends on 1)

The MnAl alloy as claimed in claim 1, wherein the MnAl alloy is in a powder form.

### Claim 7 (depends on 6)

The MnAl alloy as claimed in claim 6, wherein the MnAl alloy has a predetermined shape by molding a powdery MnAl alloy.

### Claim 8 (depends on 1)

An electronic component including the MnAl alloy as claimed in claim 1.

### Claim 9 (depends on 1)

A method for manufacturing the MnAl alloy of claim 1, the method comprising:
depositing the MnAl alloy by electrolyzing molten salt containing a Mn compound and an Al compound; and
applying heat treatment to the MnAl alloy at a temperature of 400° C. or more and less than 600° C.

### Claim 10

A MnAl alloy formed by subjecting Mn and Al to temperature-controlled electrolysis and heat treatment that result in the MnAl alloy exhibiting metamagnetism.