Rapid Consolidation of Gamma Titanium Aluminide Powders Attrition Milled to Submicron Scale

Abstract

Commercially available micron-sized gamma titanium aluminide powders with Ti-50%Al and Ti-48%Al-2%Cr-2%Nb (at%) composition were milled in an attrition mill for 5 hours and 8 hours, respectively, with 2 wt% stearic acid. Milling resulted in a decrease of the average powder particle size by 60%, which implies submicrometer range powders, with no change in the powder composition. The milled powders were consolidated to produce a near-gamma microstructure and fully lamellar microstructure for Ti-50%Al and Ti-48%Al-2%Cr-2%Nb composition samples, respectively. A significant decrease in grain size was realized for the samples consolidated from the milled powders as compared to samples consolidated from as-received powders. The decrease in grain size improved flexure strength and elongation.

Keywords:

• Attrition milling
• Grain refinement
• Intermetallics
• Powder metallurgy
• Rapid consolidation
• Titanium aluminide

ACKNOWLEDGMENTS

This work was supported by the Space Vehicle Technology Institute under grant NCC3-989 jointly funded by National Aeronautics and Space Administration (NASA) and U.S. Department of Defense within the NASA Constellation University Institutes Project. The authors would like to thank Prof. Mark Lewis (University of Maryland) and Ms. Claudia M. Meyer (NASA) for their encouragement and insights.