On grain refinement of a γ-TiAl alloy using cryo-milling followed by spark plasma sintering

• Published in: Intermetallics Vol. 66; pp. 141 - 148
• Main Authors: Shanmugasundaram, T., Guyon, J., Monchoux, J.P., Hazotte, A., Bouzy, E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2015; Elsevier
• Subjects: Chemical Sciences; Cryo-milling; Densification; Engineering Sciences; Grain refinement; Grain size; Intermetallic compounds; Intermetallics; Material chemistry; Microstructure; Phase transformation; Phases; Spark plasma sintering; Titanium aluminides; Cryo-milling; Phase transformation; Spark plasma sintering; Titanium aluminides; Microstructure
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2015.07.007

A fully dense fine-grained γ-TiAl based alloy was fabricated by cryo-milling pre-alloyed powders followed by spark plasma sintering. The consolidation was performed at 1050 or 1200 °C. The effect of cryo-milling on the densification kinetics and final microstructure was studied. Results indicate that cryo-milled (8 h) powder is fully densified at a temperature nearly 125 °C lower than that of un-milled powder. The microstructure of the alloy fabricated at different temperatures consisted of fine grains of γ-TiAl and α2 (Ti3Al) phases in different volume fractions. The average grain size of cryo-milled powders compacted at 1050 and 1200 °C were determined as 0.6 and 0.9 μm, respectively. It is inferred that the reduction in crystallite and particle size induced by cryo-milling is the likely reason for such enhancement in densification and grain refinement. •The effect of cryo-milling enhances the SPS densification.•Fully dense compacts can be produced at a lower temperature after cryomilling.•Coupling cryomilling and low temperature SPS results in smaller grain size.•Volume fraction of the α2 phase can be controlled by SPS holding temperature.