Passivation and alloying element retention in gas atomized powders
A method for gas atomization of a titanium alloy, nickel alloy, or other alumina (Al 2 O 3 )-forming alloy wherein the atomized particles are exposed as they solidify and cool in a very short time to multiple gaseous reactive agents for the in-situ formation of a passivation reaction film on the atomized particles wherein the reaction film retains a precursor halogen alloying element that is subsequently introduced into a microstructure formed by subsequent thermally processing of the atomized particles to improve oxidation resistance.
1. A body made from consolidated titanium-aluminum alloy atomized particles each having, before consolidation, an outer surface layer comprising an outermost oxy-fluoride layer region formed on an innermost oxygen-containing layer region that is formed first by exposure of surfaces of the atomized particles to an oxygen-bearing gas, wherein the body has a microstructure having fluoride of the outermost oxy-fluoride layer region present in the microstructure in an amount to improve oxidation resistance.
2. The body of claim 1 wherein, after consolidation of the atomized particles, fluoride is present in solid solution and/or as a fluoride-enriched precipitate in the microstructure.
3. The body of claim 1 which is thermally processed.
4. The body of claim 3 wherein the thermally processed body exists in at least one condition of being hot isostatic pressed, sintered, hot extruded, and hot metal particle injected.
5. A body made from consolidated nickel-aluminum alloy atomized particles each having, before consolidation, an outer surface layer comprising an outermost oxy-fluoride layer region formed on an innermost oxygen-containing layer region that is formed first by exposure of surfaces of the atomized particles to an oxygen-bearing gas, wherein the body has a microstructure having fluoride of the outermost oxy-fluoride layer region present in the microstructure in an amount to improve oxidation resistance.
6. The body of claim 5 wherein, after consolidation of the atomized particles, fluoride is present in solid solution and/or as a fluoride-enriched precipitate in the microstructure.
7. The body of claim 5 which is thermally processed.
8. The body of claim 7 wherein the thermally processed body exists in at least one condition of being hot isostatic pressed, sintered, hot extruded, and hot metal particle injected.