Fabrication of metallic parts by additive manufacturing

1. A method of fabricating a three-dimensional part comprising molybdenum, the method comprising:

(a) compacting powder to form a feed electrode, the powder comprising molybdenum;

(b) arc-melting the feed electrode in a processing ambient comprising a vacuum or one or more inert gases, thereby forming a billet;

(c) mechanically deforming the billet into wire having a diameter less than a diameter of the billet;

(d) translating a tip of the wire relative to a platform;

(e) while the tip of the wire is being translated, melting the tip of the wire with an energy source to form a molten bead, whereby the molten bead cools to form at least a portion of a layer of a three-dimensional part; and

(f) repeating steps (d) and (e) one or more times to produce the three-dimensional part,

wherein the three-dimensional part comprises molybdenum.

2. The method of claim 1 , wherein a concentration within the wire of at least one of sodium, calcium, antimony, magnesium, phosphorous, or potassium is less than 5 ppm by weight.

3. The method of claim 1 , wherein a concentration of oxygen within the wire is less than 20 ppm by weight.

4. The method of claim 1 , wherein a density of the three-dimensional part is greater than 97% of a theoretical density of molybdenum.

5. The method of claim 1 , wherein a density of the three-dimensional part is greater than 99% of a theoretical density of molybdenum.

6. The method of claim 1 , wherein step (c) comprises at least one of drawing, rolling, swaging, extruding, or pilgering.

7. The method of claim 1 , wherein step (a) comprises sintering the compacted powder at a temperature greater than 900° C.

8. The method of claim 1 , wherein in step (e) the energy source comprises an electron beam and/or a laser beam.

9. The method of claim 1 , further comprising, prior to step (a), providing the powder by a process comprising at least one of plasma densification or plasma atomization.

10. A method of fabricating a three-dimensional part comprising molybdenum utilizing wire produced by a process comprising (i) compacting powder to form a feed electrode, the powder comprising molybdenum, (ii) arc-melting the feed electrode in a processing ambient comprising a vacuum or one or more inert gases, thereby forming a billet, and (iii) mechanically deforming the billet into wire having a diameter less than a diameter of the billet, the method comprising:

(a) translating a tip of the wire relative to a platform;

(b) while the tip of the wire is being translated, melting the tip of the wire with an energy source to form a molten bead, whereby the molten bead cools to form at least a portion of a layer of a three-dimensional part; and

(c) repeating steps (a) and (b) one or more times to produce the three-dimensional part,

wherein the three-dimensional part comprises molybdenum.

11. The method of claim 10 , wherein a concentration within the wire of at least one of sodium, calcium, antimony, magnesium, phosphorous, or potassium is less than 5 ppm by weight.

12. The method of claim 10 , wherein a concentration of oxygen within the wire is less than 20 ppm by weight.

13. The method of claim 10 , wherein a density of the three-dimensional part is greater than 97% of a theoretical density of molybdenum.

14. The method of claim 10 , wherein a density of the three-dimensional part is greater than 99% of a theoretical density of molybdenum.

15. The method of claim 10 , wherein mechanically deforming the billet into wire comprises at least one of drawing, rolling, swaging, extruding, or pilgering.

16. The method of claim 10 , wherein the process of producing the wire comprises sintering the compacted powder at a temperature greater than 900° C.

17. The method of claim 10 , wherein in step (b) the energy source comprises an electron beam and/or a laser beam.

18. The method of claim 10 , wherein the process of producing the wire comprises providing the powder by a process comprising at least one of plasma densification or plasma atomization.