Method of manufacturing a bulk nitride, carbide, or boride-containing material

Patent metadata

Field	Value
Publication number	US-11031161-B2
Application number	US-201815977545-A
Country	US
Kind code	B2
Filing date	May 11, 2018
Priority date	May 11, 2018
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A three-dimensional object made of a bulk nitride, carbide, or boride-containing material may be manufactured using a powder bed fusion additive manufacturing technique. A layer of powder feed material may be distributed over a solid substrate and scanned with a high-energy laser beam to locally melt selective regions of the layer and form a pool of molten feed material. The pool of molten feed material may be exposed to gaseous nitrogen, carbon, or boron to respectively dissolve nitride, carbide, or boride ions into the pool of molten feed material to produce a molten nitrogen, carbon, or boron-containing solution. The molten nitrogen, carbon, or boron-containing solution may cool and solidify into a solid layer of fused nitride, carbide, or boride-containing material. In one form, the three-dimensional object may comprise a permanent magnet made up of a plurality of solid layers of fused iron nitride material having a magnetic Fe16N2 phase.

First claim

What is claimed is:

1. A method of manufacturing a three-dimensional object made of a bulk nitride-containing material using a powder bed fusion additive manufacturing technique, the method comprising:
(a) providing a powder feed material including iron (Fe);
(b) distributing a layer of the powder feed material over a solid substrate;
(c) scanning selective regions of the layer of the powder feed material with a laser beam to locally melt the selective regions and form a pool of molten feed material, the selective regions of the layer corresponding to a cross-section of a three-dimensional object being formed;
(d) exposing the pool of molten feed material to gaseous nitrogen to dissolve nitride ions into the pool of molten feed material to produce a molten solution of iron and nitrogen;
(e) terminating the laser beam to cool and solidify the molten solution into a solid layer of fused iron nitride material; and
repeating steps (b) through (e) to form a three-dimensional permanent magnet made up of a plurality of solid layers of fused iron nitride material,
wherein the fused iron nitride material comprises a magnetic Fe 16 N 2 phase, and
wherein, during formation of the plurality of solid layers of fused iron nitride material, thermal gradients are repeatedly generated within the solid layers such that the three-dimensional permanent magnet exhibits localized strains in the range of 0.5% to 1%, and wherein the localized strains promote formation and stabilization of the magnetic Fe 16 N 2 phase.

2. The method of claim 1 wherein step (d) includes:
directing a gas stream at the pool of molten feed material, wherein the gas stream comprises at least one of urea (CO(NH 2 ) 2 ), ammonia (NH 3 ), or nitrogen (N 2 ).

3. The method of claim 1 wherein steps (b) through (f) are performed within a chamber, and wherein step (d) includes:
introducing a nitrogen-containing gas into the chamber; and
establishing a high-pressure environment within the chamber, the high-pressure environment exhibiting a pressure in the range of 150 kPa to 150 MPa.

4. The method of claim 1 wherein steps (b) through (f) are performed within a chamber, and wherein step (d) includes:
introducing a nitrogen-containing gas into the chamber;
generating an electric field within the chamber to ionize the nitrogen-containing gas and transform the gas into a plasma;
establishing a subatmospheric pressure environment within the chamber; and
establishing an electric potential difference between the solid substrate and the plasma to attract nitrogen ions to the pool of molten feed material.

5. The method of claim 1 wherein, when the selective regions of the layer are scanned with the laser beam, a volume of solid material underlying the selective regions of the layer does not melt and is maintained at a temperature less than 500° C.

6. The method of claim 5 wherein, upon termination of the laser beam, the pool of molten feed material is quenched by heat transfer from the pool of molten feed material to the volume of solid material underlying the selective regions of the layer.

7. The method of claim 1 wherein, upon termination of the laser beam, the pool of molten feed material is cooled at a rate in the range of 10 4 Kelvin per second to 10 6 Kelvin per second.

8. The method of claim 1 wherein, during formation of the plurality of solid layers of fused iron nitride material, thermal gradients are repeatedly generated within the solid layers such that the three-dimensional permanent magnet made up of the plurality of solid layers exhibits localized regions of residual stress.

9. The method of claim 1 wherein the powder feed material comprises, by weight, greater than or equal to 90% iron (Fe).

10. The method of claim 9 wherein the powder feed material comprises at least one nonmetal element selected from the group consisting of nitrogen, carbon, or boron, and wherein each particle of the powder feed material comprises the at least one nonmetal element in an amount, by weight, less than or equal to 5%.

11. The method of claim 1 wherein the fused iron nitride material comprises, on an atomic basis, greater than 10% nitrogen and the magnetic Fe 16 N 2 phase exhibits a body-centered tetragonal (bct) crystal structure.

12. The method of claim 1 wherein the three-dimensional permanent magnet comprises a solid exterior and a porous interior enclosed within the solid exterior.

13. The method of claim 1 including:
after step (f), exposing the three-dimensional permanent magnet to gaseous nitrogen, carbon, or boron to increase the respective concentration of nitrogen, carbon, or boron within the solid layers of fused iron nitride material.

14. The method of claim 13 wherein the three-dimensional permanent magnet comprises a plurality of flow-through channels defined by walls having wall surfaces, and wherein, when the three-dimensional permanent magnet is exposed to gaseous nitrogen, carbon, or boron, the gaseous nitrogen, carbon, or boron is directed through the flow-through channels in the three-dimensional permanent magnet such that the gaseous nitrogen, carbon, or boron contacts the wall surfaces and promotes dissolution of nitride, carbide, or boride ions into the solid layers of fused iron nitride material.

15. A method of manufacturing a three-dimensional permanent magnet using a powder bed fusion additive manufacturing technique, the method comprising:
(a) providing an iron-based powder feed material;
(b) distributing a layer of the powder feed material over a solid substrate;
(c) scanning selective regions of the layer of the powder feed material with a laser beam to locally melt the selective regions and form a pool of molten feed material, the selective regions of the layer corresponding to a cross-section of a three-dimensional object being formed;
(d) exposing the pool of molten feed material to gaseous nitrogen to dissolve nitride ions into the pool of molten feed material;
(e) terminating the laser beam to cool and solidify the pool of molten feed material into a solid layer of fused iron nitride material; and
(f) repeating steps (b) through (e) to form a three-dimensional object made up of a plurality of solid layers of fused iron nitride material,
wherein the fused iron nitride material comprises, on an atomic basis, greater than 10% nitrogen,
wherein the fused iron nitride material comprises a magnetic Fe 16 N 2 phase exhibiting a body-centered tetragonal (bct) crystal structure, and
wherein, during formation of the plurality of solid layers of fused iron nitride material, thermal gradients are repeatedly generated within the solid layers such that the three-dimensional object exhibits localized strains in the range of 0.5% to 1%, and wherein the localized strains promote formation and stabilization of the magnetic Fe 16 N 2 phase.

16. The method of claim 15 wherein the three-dimensional object is trapezoid-shaped, or helical in shape.

17. A method of manufacturing a three-dimensional permanent magnet made of a bulk nitride-containing material using a powder bed fusion additive manufacturing technique, the method comprising:
(a) providing a powder feed material including iron (Fe);
(b) distributing a layer of the powder feed material over a solid substrate;
(c) scanning selective regions of the layer of the powder feed material with a laser beam to locally melt the selective regions and form a pool of molten feed material, the selective regions of the layer corresponding to a cross-section of a three-dimensional object being formed;
(d) exposing the pool of molten

Assignees

• Gm Global Tech Operations Llc

Inventors

• Sachdev Anil K
• Pinkerton Frederick E
• Mishra Raja K
• Brown Tyson W

Classifications

• C22C1/1063

  Gas reaction, e.g. lanxide · CPC title

• H01F1/0311 Primary

  Compounds (H01F1/0304 takes precedence) · CPC title

• B29C64/153 Primary

  using layers of powder being selectively joined, e.g. by selective laser sintering or melting · CPC title

• B22F12/70

  Gas flow means · CPC title

• B22F10/62

  by chemical means · CPC title