Method for forming high quality powder for an additive manufacturing process

1. A method of treating a feedstock powder of feedstock particles in a powder treatment assembly, the method comprising:

directing the feedstock powder from a feedstock discharge nozzle into a plasma chamber within a reactor of the powder treatment assembly;

exposing the feedstock powder to a plasma field generated by a plasma source within the plasma chamber to form a treated powder having treated particles with an increased sphericity relative to the feedstock particles, wherein the plasma source comprises a plurality of plasma torches; and

supplying downstream of the plasma chamber a hot gas sheath flow that surrounds the treated powder.

2. The method of claim 1 , wherein the hot gas sheath flow

is discharged into a distribution chamber defined around the plasma chamber, before being supplied downstream of the plasma chamber to surround the treated powder.

3. The method of claim 1 , wherein the sphericity is measured using ISO 9276-6.

4. The method of claim 3 , wherein an average sphericity of the sphericity of treated powder is greater than 0.85.

5. The method of claim 1 , wherein the plurality of plasma torches generates a plurality of plasma jets, respectively.

6. The method of claim 5 , wherein each plasma jet of the plurality of plasma jets is directed at an angle relative to a flow direction of the feedstock powder to converge at a focal point below the feedstock discharge nozzle.

7. The method of claim 6 , further comprising:

moving the feedstock discharge nozzle along a vertical direction within the plasma chamber.

8. The method of claim 6 , further comprising:

providing a flow of cooling fluid through a cooling path defined in a wall of the feedstock discharge nozzle for regulating a temperature of the feedstock discharge nozzle.

9. The method of claim 6 , wherein the focal point is located at a chamber inlet defined on a top of the plasma chamber.

10. The method of claim 1 , further comprising:

distributing the hot gas sheath flow within a distribution chamber defined around the plasma chamber.

11. The method of claim 10 , wherein the hot gas sheath flow is cylindrical.

12. The method of claim 10 , wherein the plasma chamber and the distribution chamber are defined by a central body positioned within the reactor.

13. The method of claim 12 , wherein the central body is formed from graphite.

14. The method of claim 1 , wherein the hot gas sheath flow comprises argon.

15. The method of claim 1 , wherein exposing the feedstock powder to the plasma field comprises:

introducing the feedstock powder into the plasma field such that at least a portion a surface of the feedstock particles melts or evaporates to increase the sphericity of the feedstock particles.

16. The method of claim 1 , wherein the feedstock particles have a maximum size of about 150 μm.

17. The method of claim 16 , wherein the feedstock particles have an average feedstock size of about 10 μm to about 150 μm.

18. The method of claim 17 , wherein the treated particles have an average particle size that is less than an average feedstock size of the feedstock particles.

19. The method of claim 17 , wherein the treated particles have an average particle size that is about 10% to about 90% of the average feedstock size of the feedstock particles.

20. The method of claim 1 , wherein the feedstock powder comprises a pure metal, an iron alloy, a titanium, an aluminum alloy, a nickel alloy, a chrome alloy, a nickel-based superalloy, an iron-based superalloy, a cobalt-based superalloy, or a mixture thereof.