Method of making a powder metal compact

1. A method of making a selectively corrodible article, comprising:

forming a powder comprising a plurality of metallic powder particles, each metallic powder particle comprising a nanoscale metallic coating layer disposed on a particle core, the metallic coating layer having a substantially uniform thickness of 25 to 2500 nm; and

forming a powder compact of the powder particles by deforming the powder particles such that they are substantially elongated in a predetermined direction to form substantially elongated powder particles and the coating layers form a substantially elongated cellular nanomatrix, the powder compact comprising an article that is selectively corrodible in response to a change in a predetermined wellbore fluid, the powder compact having an ultimate compressive strength or corrosion rate in the predetermined wellbore fluid that is greater than a powder compact of the metallic particles that comprises a cellular nanomatrix that is not substantially elongated.

2. The method of claim 1 , wherein the coating layers of the substantially elongated particles are substantially discontinuous in the predetermined direction.

3. The method of claim 1 , wherein forming the powder compact comprises extruding the powder.

4. The method of claim 1 , wherein extruding is performed according to a predetermined reduction ratio.

5. The method of claim 4 , wherein the predetermined reduction ratio is about 5 to about 2000.

6. The method of claim 1 , wherein forming the powder compact is performed at a forming temperature that is less than a melting temperature of the powder compact.

7. The method of claim 6 , wherein the forming temperature is about 20° C. to about 300° C. below the melting temperature of the powder compact.

8. The method of claim 1 , wherein the particle core comprises a particle core material comprising Mg, Al, Zn or Mn, or a combination thereof.

9. The method of claim 1 , wherein the metallic coating layer comprises a coating material comprising Al, Zn, Mn, Mg, Mo, W, Cu, Fe, Si, Ca, Co, Ta, Re or Ni, or an oxide, carbide, nitride, intermetallic, or cermet thereof, or a combination of any of the aforementioned materials, and wherein the coating material has a chemical composition and the particle core material has a chemical composition that is different than the chemical composition of the coating material.

10. The method of claim 8 , wherein the metallic coating layer comprises a coating material comprising Al, Zn, Mn, Mg, Mo, W, Cu, Fe, Si, Ca, Co, Ta, Re or Ni, or an oxide, carbide, nitride, intermetallic, or cermet thereof, or a combination of any of the aforementioned materials, and wherein the coating material has a chemical composition and the particle core material has a chemical composition that is different than the chemical composition of the coating material.

11. The method of claim 10 , wherein the particle core material comprises Mg and the metallic coating layer comprises Al or Ni, or a combination thereof.

12. The method of claim 10 , wherein forming the powder compact is performed at a forming temperature of about 300° F. to about 1000° F.

13. The method of claim 10 , wherein the powder compact has an ultimate compressive strength greater than about 50 ksi.

14. The method of claim 1 , wherein forming the powder compact comprises:

compacting the powder particles into a billet; and

deforming the billet to form the powder compact and form the substantially elongated powder particles and the substantially elongated cellular nanomatrix.

15. The method of claim 14 , deforming the billet comprises extruding, roll forming or forging the billet.

16. The method of claim 14 , wherein deforming the billet is performed according to a predetermined reduction ratio.

17. The method of claim 16 , wherein the predetermined reduction ratio is about 5 to about 2000.

18. The method of claim 17 , wherein the predetermined reduction ratio is about 50 to about 1000.

19. The method of claim 14 , wherein compacting the powder particles into the billet comprises cold pressing the powder particles into the billet, wherein the billet comprises a green-state powder compact.

20. The method of claim 14 , wherein compacting the powder particles into the billet comprises forging the powder particles into the billet.

21. The method of claim 14 , wherein compacting the powder particles into the billet comprises roll forming the powder particles into the billet.

22. The method of claim 1 , wherein the powder compact having the substantially elongated powder particles has a rate of corrosion in a predetermined wellbore fluid that is greater than a rate of corrosion of the billet.

23. The method of claim 22 , wherein the predetermined wellbore fluid comprises water, an acid, an aqueous salt solution or a brine, or a combination thereof.

24. The method of claim 1 , wherein the particle cores have an average diameter of about 50 nm to about 500 μm and the metallic coating layers have an average thickness of about 25 nm to about 2500 nm.

25. The method of claim 1 , wherein metallic coating layer comprises a plurality of metallic coating layers.

26. The method of claim 1 , wherein the article is a downhole article and comprises a downhole tool or component.

27. The method of claim 26 , wherein the downhole tool or component comprises a ball, plug, sleeve, tubular, or seat.