Production of amorphous metallic foam by powder consolidation

Patent metadata

Field	Value
Publication number	US-RE47748-E
Application number	US-201113267063-A
Country	US
Kind code	E1
Filing date	Oct 6, 2011
Priority date	Jan 21, 2005
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

The formation of amorphous porous bodies and in particular to a method of manufacturing such bodies from amorphous particulate materials. The method allows for the control of the volume fraction as well as the spatial and size distribution of gas-formed pores by control of the size distribution of the powder particulates. The method allows for the production of precursors of unlimited size, and because the softened state of the amorphous metals used in the method possesses visco-plastic properties, higher plastic deformations can be attained during consolidation as well as during expansion.

First claim

What is claimed is:

1. A method of forming an amorphous metal foam formed of an amorphous metal powder comprising:
mixing at least one amorphous metal powder and at least one gas-splitting propellant powder into a propellant filled amorphous metal powder mixture, such that upon decomposition of the gas-splitting propellant powder, gas-containing pores are created within the amorphous metal powder mixture;
compacting the mixture such that the amorphous metal powder particles are bonded to one another to form a gas-tight seal around the gas-splitting propellant powder particles, the mixture being compacted at a compacting temperature and pressure sufficient to allow for bonding of the mixture, wherein the temperature is below any crystalline transition temperature of the amorphous metal powder, and for a duration not exceeding a time for any crystalline transformation of said amorphous metal powder at the compacting temperature and pressure;
cooling the compacted mixture at a cooling rate sufficient that the amorphous metal powder mixture remains amorphous;
expanding the compacted amorphous metal powder mixture to form a foam material, said expansion being conducted at an expansion temperature below any crystalline transition temperature of the amorphous metal powder, but sufficiently high to allow bubble expansion, at a surrounding pressure sufficient to promote expansion arising from a difference between a pressure in the gas-containing pores and the surrounding pressure, and for a duration not exceeding the time for any crystalline transformation to take place; and
cooling the expanded foam material in order to allow the foam material to remain amorphous.

2. The method according to claim 1 wherein the gas-splitting propellant powder decomposes during expansion.

3. The method according to claim 1 wherein the gas-splitting propellant powder decomposes during compaction.

4. The method according to claim 1 wherein heat and pressure are simultaneously suspended after the compacting and cooling of the compacted mixture takes place without the influence of pressure.

5. The method according to claim 1 wherein the powder mixture further comprises strength reinforcing components.

6. The method according to claim 5 wherein the compacting is followed by aligning the strength reinforcing components.

7. The method according to claim 1 wherein the compacting is performed by a method selected from the group consisting of: hot pressing, hot extrusion, hot forging, hot rolling and dyna-packing.

8. The method according to claim 1 wherein the amorphous metal powder is selected from the group consisting of Zr based alloys, Ti based alloys, Al based alloys, Fe based alloys, La based alloys, Cu based alloys, Mg based alloys, Pt based alloys and Pd based alloys.

9. The method according to claim 1 wherein at least two different gas-splitting propellant powders with different decomposition temperatures are used.

10. The method according to claim 1 wherein the compacting takes place in a mold such that the powder mixture is completely or partially surrounded by a propellant-free metal or amorphous metal powder.

11. The method according to claim 1 wherein the compacting is accomplished by extrusion molding, with the powder mixture being piled against a propellant-free metal piece.

12. The method according to claim 1 wherein a porous metal body is made by expanding the compacted mixture, said expansion being conducted at an expansion temperature below any crystalline transition temperature of the amorphous metal but above a glass transition temperature of the amorphous metal powder, followed by cooling of the porous metal body to thereby form a foam.

13. The method according to claim 1 wherein a porous metal body is made by expanding the compacted mixture, said expansion being conducted at an expansion temperature below any crystalline transition temperature of the amorphous metal powder, whereby during expansion of the compacted mixture, different temperature and time values are used as a function of a density of the porous metal body to be produced, followed by cooling of the porous metal body to thereby form a foam.

14. The method according to claim 1 wherein a porous metal body is made by expanding the compacted mixture, said expansion being conducted at an expansion temperature below any crystalline transition temperature of the amorphous metal powder, with a heating rate being between 1° and 5° C./sec, followed by cooling of the porous metal body at a rate sufficient to interrupt further foaming of the porous metal body.

15. The method according to claim 1 wherein the gas-splitting propellant powder is selected from the group consisting of: water vapor-releasing agents, hydrogen-releasing agents, carbon monoxide-releasing agents, carbon dioxide-releasing agents, and nitrogen-releasing agents.

16. The method of claim 1 , further comprising forming the amorphous metal particles prior to the mixing step, wherein the forming the amorphous metal particles comprises heating a crystalline metal or alloy above a melting temperature of the crystalline metal or alloy such that the crystalline metal or alloy melts, and then rapidly cooling the melted crystalline metal or alloy to prevent recrystallization.

17. A method of forming an amorphous metal foam formed of an amorphous metal powder comprising:
placing an amorphous metal powder in a gas-tight chamber, and pressurizing the chamber with a pressurizing gas at a pressure sufficient to compact and bond the powder around gas-containing pores;
heat treating the compacted powder to increase a pressure of the gas within the gas-containing pores at a temperature and pressure sufficient to allow for a visco-plastic deformation of the powder, wherein the temperature is below any crystalline transition temperature of the amorphous metal, and for a duration not exceeding a time for any crystalline transformation of said amorphous metal powder;
cooling the compacted powder at a cooling rate sufficient to retain the amorphous state of the powder;
expanding the compacted powder to form a foam material, said expansion being conducted at an expansion temperature below any crystalline transition temperature of the metal powder, but sufficiently high to allow visco-plastic deformation during bubble expansion, at a surrounding pressure sufficient to promote expansion arising from a difference between a pressure in the gas-containing pores and the surrounding pressure, and for a duration not exceeding the time for any crystalline transformation to take place; and
cooling the expanded foam material such that the material remains amorphous.

18. The method of claim 17 wherein the pressure of the chamber is from vacuum to over 100 atm.

19. The method of claim 17 wherein the pressure within the gas-containing pores is from about vacuum to over 2000 atm.

20. The method of claim 17 wherein the gas is selected from the group consisting of: helium, argon, air, nitrogen, and hydrogen.

21. The method according to claim 17 wherein compacting is performed by a method selected from the group consisting of: hot pressing, hot extrusion, hot forging, hot rolling and dyna-packing.

22. The method according to claim 17 wherein the amorphous metal powder is selected from the group consisting of Zr based alloys, Ti based alloys, Al based alloys, Fe based alloys, La based alloys, Cu based alloys, Mg based alloys, Pt based alloys and Pd based alloys.

23. A method co

Assignees

• Demetriou Marios
• Johnson William L
• Veazey Christopher Thomas
• Schroers Jan
• California Inst Of Techn

Inventors

• Demetriou Marios
• Johnson William L
• Veazey Christopher Thomas
• Schroers Jan

Classifications

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title

• Y10T428/12479

  Porous [e.g., foamed, spongy, cracked, etc.] · CPC title

• B22F3/1125 Primary

  involving a foaming process · CPC title

• B22F9/002

  amorphous or microcrystalline · CPC title

• B22F3/02

  Compacting only · CPC title