Porosity reduction in inert-gas atomized powders
AssigneeThe International Nickel Company, Inc.
InventorsJay Michael Larson, Ian Sidney Rex Clark, Robert Cameron Gibson
Life of this patent
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Abstract
Thermally induced porosity, which can lead to cracking in metal powders after consolidation, is believed to be caused by the entrapment of the inert gas used for atomization within the metal powders. The addition of an activating agent to the molten alloy prior to atomization with an inert gas, such as argon, serves to substantially reduce the porosity of metal powders. Suitable activating agents are characterized by an ability to rapidly diffuse to the surface of a molten metal particle and an affinity for oxygen. Activating agents that are useful for high nickel alloys and highly alloyed steels include magnesium, calcium, lithium, silicon, and rare earths.
Claims14
A process for substantially reducing gas entrapment in an inert gas atomized metal powder comprising:
- melting a metal alloy, activating said metal alloy by addition of from about 0.001 to about 0.1% by weight of an activating agent, selected from the group consisting of magnesium, calcium, lithium, silicon, and rare earths and atomizing said metal alloy containing said activating agent by contact with a high velocity inert gas.
An inert gas atomized metal powder containing, in weight percent, less than about 0.03% of an atomizing gas, and from 0.001 to about 0.1% of at least one activating agent selected from the group consisting of magnesium, calcium, lithium, silicon, and rare earths, said at least one activating agent concentrated on the surface of said metal powder.
Dependencies are inferred from the claim text.