Production of amorphous metallic foam by powder consolidation
AssigneeCalifornia Institute of Technology
InventorsMarios Demetriou, William L. Johnson, Christopher Thomas Veazey, Jan Schroers
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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.
Claims22
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;
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- cooling the expanded foam material in order to allow the foam material to remain amorphous.
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.
Dependencies are inferred from the claim text.