Applied magnetic field synthesis and processing of iron nitride magnetic materials

Patent metadata

Field	Value
Publication number	US-2018100227-A1
Application number	US-201715840747-A
Country	US
Kind code	A1
Filing date	Dec 13, 2017
Priority date	Jun 30, 2014
Publication date	Apr 12, 2018
Grant date	—

Abstract

A method may include annealing a material including iron and nitrogen in the presence of an applied magnetic field to form at least one Fe 16 N 2 phase domain. The applied magnetic field may have a strength of at least about 0.2 Tesla (T).

First claim

1 . A method comprising:
annealing a material including iron and nitrogen in the presence of an applied magnetic field to form at least one Fe 16 N2 phase domain, wherein the applied magnetic field has a strength of at least about 0.2 Tesla (T).

2 . The method of claim 1 , wherein the strength of the high magnetic field is greater than about 2.5 T.

3 . The method of claim 1 , wherein the strength of the high magnetic field is between about 8 T and about 10 T.

4 . The method of claim 1 , wherein the strength of the high magnetic field is greater than about 9 T.

5 . The method of claim 1 , wherein annealing the material comprises heating the material at a temperature of between about 120° C. to about 200° C. for between about 10 hours and about 100 hours.

6 . The method of claim 5 , wherein annealing the material comprises heating the material at a temperature between about 150° C. and about 160° C. for between about 10 hours and about 30 hours.

7 . The method of claim 1 , wherein the material comprises at least one of a pellet, rod, thin film, nanoparticle, powder, or nanoscale powder.

8 . The method of claim 1 , wherein the material further comprises at least one dopant.

9 . The method of claim 8 , wherein the at least one dopant comprises at least one of Al, Mn, La, Cr, Co, Ti, Ni, or a rare earth metal.

10 . The method of claim 8 , wherein the at least one dopant comprises at least one of B, C, P, Si, or O.

11 . The method of claim 1 , wherein annealing the material in the presence of the applied magnetic field transforms an {acute over (α)}-Fe 8 N phase in the material to an {acute over (α)}-Fe 16 N2 phase.

12 . The method of claim 11 , wherein a transformation yield of the {acute over (α)}-Fe 8 N phase to the {acute over (α)}-Fe 16 N2 phase is at least 70%.

13 . The method of claim 1 , wherein, after annealing, the {acute over (α)}-Fe 16 N 2 phase in the material is at least 20% of the material by volume.

14 . The method of claim 1 , wherein the applied magnetic field is applied in substantial alignment with a c axis of at least one iron crystal in the material.

15 . The method of claim 1 , further comprising:
prior to annealing the material, solutionizing the material in the presence of an applied magnetic field with a strength of at least about 0.2 T; and after solutionizing the material, quenching the material.

16 . (canceled)

17 . The method of claim 1 , wherein, prior to annealing the material, the concentration of nitrogen in the material is between about 8 atomic percent (at. %) and about 9 at.

18 . A method comprising:
nitridizing a material including iron in the presence of an applied magnetic field to form an iron-nitride-containing material; and annealing the iron-nitride-containing material in the presence of the applied magnetic field to form at least one Fe16N2 phase domain, wherein the applied magnetic field has a strength of at least about 0.2 Tesla (T).

19 . The method of claim 18 , wherein the material including iron comprises an iron-based powder or iron-based nanoscale powder.

20 . The method of claim 18 , wherein the material comprises at least one of an iron oxide, iron carbide, iron chloride, or iron-metal solid solution.

21 . The method of claim 18 , wherein nitridizing the material and annealing the iron nitride-containing material to form at least one Fe16N2 phase domain occur in situ in the presence of the applied magnetic field.

22 . The method of claim 18 , further comprising, prior to nitridizing the material, reducing the material in at least one of hydrogen, nitrogen, or ammonia gas, wherein reduction of the material occurs in situ in the presence of the applied magnetic field.

23 . The method of claim 22 , wherein reducing the material comprises reducing a carbon coated iron powder in hydrogen gas for about 1 hour at a temperature of between about 375° C. and about 425° C.

24 . The method of claim 18 , wherein the strength of the high magnetic field is greater than about 2.5 T.

25 . The method of claim 18 , wherein the strength of the high magnetic field is between about 8 T and about 10 T.

26 . The method of claim 18 , wherein the strength of the high magnetic field is greater than about 9 T.

27 . The method of claim 18 , wherein annealing the iron-nitride-containing material comprises heating the iron-nitride-containing material at a temperature of between about 100° C. to about 250° C. for between about 10 hours and about 100 hours.

28 . The method of claim 18 , wherein the iron-nitride-containing material further comprises at least one dopant.

29 . The method of claim 28 , wherein the at least one dopant comprises at least one of Al, Mn, La, Cr, Co, Ti, Ni, or a rare earth metal.

30 . The method of claim 28 , wherein the at least one dopant comprises at least one of B, C, P. Si, or O.

31 . The method of claim 18 , wherein annealing the iron-nitride-containing material in the presence of the applied magnetic field transforms an {acute over (α)}-Fe 8 N phase in the iron-nitride containing material to an {acute over (α)}-Fe 16 N2 phase.

32 . The method of claim 31 , wherein a transformation yield of the {acute over (α)}-Fe 8 N phase to the {acute over (α)}-Fe 16 N2 phase is at least 70%.

33 . The method of claim 18 , wherein, after annealing, the {acute over (α)}-Fe 16 N 2 phase in the iron nitride-containing material is at least 20% of the iron-nitride-containing material by volume.

34 . The method of claim 18 , wherein the applied magnetic field is applied in substantial alignment with a c axis of at least one iron crystal in the iron-nitride-containing material.

35 . A workpiece comprising iron nitride material made by annealing a material including iron and nitrogen in the presence of an applied magnetic field to form at least one Fe16N2 phase domain, wherein the applied magnetic field has a strength of at least about 0.2 Tesla (T).

36 . The work piece of claim 35 , wherein the workpiece is a pellet, rod, thin film, nanoparticle, powder, or nanoscale powder.

37 . An article comprising a plurality of workpieces, wherein at least one workpiece of the plurality of workpieces comprise iron nitride material made by annealing a material including iron and nitrogen in the presence of an applied magnetic field to form at least one Fe16N2 phase domain, wherein the applied magnetic field has a strength of at least about 0.2 Tesla (T), and wherein the at least one workpiece is a pellet, rod, thin film, nanoparticle, powder, or nanoscale powder.

38 . The article of claim 37 , wherein the workpieces are arranged so the <001> axes of the respective iron nitride materials are substantially aligned.

39 . The article of claim 38 , wherein the article is an electric motor, a generator, a sensor, an actuator, a component of an automotive vehicle, or a component of a wind turbine.

Assignees

• Univ Minnesota
• Ut Battelle Llc

Inventors

• Brady Michael P
• Rios Orlando
• Jiang Yanfeng
• Ludtka Gerard M
• Bridges Craig A
• Wang Jian-Ping
• Zhang Xiaowei
• Allard Lawrence F
• Lara-Curzio Edgar

Classifications

• C22C38/001

  containing N · CPC title

• C21D6/00

  Heat treatment of ferrous alloys · CPC title

• C23C8/26 Primary

  of ferrous surfaces · CPC title

• C21D1/26

  Methods of annealing · CPC title

• H01F1/047

  Alloys characterised by their composition · CPC title