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. Atomized powder particles comprising a titanium-aluminum alloy wherein the powder particles have a surface layer having an outermost region that comprises an outermost reaction product comprising an oxy-fluoride of titanium and/or aluminum and having an innermost region that comprises an innermost reaction product comprising an oxide of titanium and/or aluminum.
2. The atomized particles of claim 1 which are spherical in shape.
3. The atomized particles of claim 1 wherein the titanium-aluminum alloy comprises titanium aluminide.
4. Atomized powder particles comprising a nickel-aluminum alloy wherein the powder particles have a surface layer having an outermost region that comprises an outermost reaction product comprising an oxy-fluoride of nickel and/or aluminum and having an innermost region that comprises an innermost reaction product comprising an oxide of nickel and/or aluminum.
5. The atomized particles of claim 4 which are spherical in shape.
6. The atomized particles of claim 4 wherein the nickel-aluminum alloy comprises nickel aluminide.