Transformation enabled nitride magnets absent rare earths and a process of making the same

Patent metadata

Field	Value
Publication number	US-10867730-B2
Application number	US-201815974517-A
Country	US
Kind code	B2
Filing date	May 8, 2018
Priority date	Dec 15, 2011
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

A process for producing an ordered martensitic iron nitride powder that is suitable for use as a permanent magnetic material is provided. The process includes fabricating an iron alloy powder having a desired composition and uniformity; nitriding the iron alloy powder by contacting the material with a nitrogen source in a fluidized bed reactor to produce a nitride iron powder; transforming the nitride iron powder to a disordered martensitic phase; annealing the disordered martensitic phase to an ordered martensitic phase; and separating the ordered martensitic phase from the iron nitride powder to yield an ordered martensitic iron nitride powder.

First claim

What is claimed is:

1. A material suitable for forming an ordered α″-martensitic iron-based alloy nitride permanent magnet, the material consisting essentially of a single-phase γ-austenite iron-based alloy nitride,
wherein the single-phase γ-austenite iron-based alloy nitride has a composition consisting essentially of:
nitrogen in a range from greater than 10.3 at. % to 11.1 at. %;
an alloy element selected from the group consisting of:
chromium in a range from 0.9 at. % to 2.7 at. %;
manganese in a range from 3.1 at. % to 8.7 at. %; and
aluminum in a range from 1.7 at. % to 5.2 at. %; and

a balance of the composition is iron.

2. The material according to claim 1 , wherein the nitrogen content is 11.1 at. %.

3. The material according to claim 1 , wherein the single-phase γ-austenite iron-based alloy nitride is a single-phase solid solution having the nitrogen diffused interstitially in the lattice structure of the single-phase γ-austenite iron-based alloy nitride.

4. The material according to claim 1 , wherein the nitrogen is included in the lattice structure of the single-phase γ-austenite iron-based alloy nitride at a ratio of 16:2 metal:nitrogen.

5. The material according to claim 1 , wherein the alloy element is selected as chromium in the range from 0.9 at. % to 2.7 at. %.

6. The material according to claim 1 , wherein the alloy element is selected as manganese in the range from 3.1 at. % to 8.7 at. %.

7. The material according to claim 1 , wherein the alloy element is selected as aluminum in the range from 1.7 at. % to 5.2 at. %.

8. The material according to claim 1 , wherein the material is in powder form.

9. A material suitable for forming an ordered α″-martensitic phase iron-based alloy nitride permanent magnet, the material consisting essentially of a single-phase γ-austenite iron-based alloy nitride, wherein the single-phase γ-austenite iron-based alloy nitride has an alloy composition comprising:
nitrogen in the range from greater than 10.3 at. % to 11.1 at. %; and
an alloying element selected from the group consisting of: chromium, aluminum, and manganese;
wherein the alloying element is included in the alloy composition in an amount that enables the single-phase γ-austenite iron-based alloy nitride to be transformed to the ordered α″-martensitic phase iron-based alloy nitride permanent magnet.

10. The material according to claim 9 , wherein the alloying element is chromium, and wherein the amount of the chromium present in the alloy composition is in a range from 0.9 at. % to 2.7 at. %.

11. The material according to claim 9 , wherein the alloying element is manganese, and wherein the amount of the manganese present in the alloy composition is in a range from 3.1 at. % to 8.7 at. %.

12. The material according to claim 9 , wherein the alloying element in the alloy composition is aluminum, and wherein the amount of the aluminum present in the alloy composition is in a range from 1.7 at. % to 5.2 at. %.

13. The material according to claim 9 , wherein:
the nitrogen content present in the alloy composition is 11.1 at. %;
the alloying element present in the alloy composition is:
chromium in a range from 0.9 at. % to 2.7 at. %;
manganese in a range from 3.1 at. % to 8.7 at. %; or
aluminum in a range from 1.7 at. % to 5.2 at. %; and

a balance of the alloy composition is iron.

14. The material according to claim 1 ,
wherein the material consists of the single-phase γ-austenite iron-based alloy nitride, and
wherein the single-phase γ-austenite iron-based alloy nitride has a composition that consists of:
nitrogen in a range from greater than 10.3 at. % to 11.1 at. %;
an alloy element selected from the group consisting of:
chromium in a range from 0.9 at. % to 2.7 at. %;
manganese in a range from 3.1 at. % to 8.7 at. %; and
aluminum in a range from 1.7 at. % to 5.2 at. %; and

a balance of the composition is iron.

15. The material according to claim 9 ,
wherein the material consists of the single-phase γ-austenite iron-based alloy nitride.

Assignees

• Univ Case Western Reserve

Inventors

• Matthiesen David

Classifications

• H01F1/065 Primary

  obtained by a reduction · CPC title

• H01F1/08

  pressed, sintered, or bound together · CPC title

• C23C8/26

  of ferrous surfaces · CPC title

• C04B2235/81

  Materials characterised by the absence of phases other than the main phase, i.e. single phase materials · CPC title

• B22F2009/041

  by mechanical alloying, e.g. blending, milling · CPC title