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

A fully dense fine-grained gamma-TiAl based alloy was fabricated by cryo-milling pre-alloyed powders followed by spark plasma sintering. The consolidation was performed at 1050 or 1200 degrees C. The effect of cryomilling on the densification kinetics and final microstructure was studied. Results indicate that cryomilled (8 h) powder is fully densified at a temperature nearly 125 degrees C lower than that of un-milled powder. The microstructure of the alloy fabricated at different temperatures consisted of fine grains of gamma-TiAl and alpha(2) (Ti3Al) phases in different volume fractions. The average grain size of cryo-milled powders compacted at 1050 and 1200 degrees C were determined as 0.6 and 0.9 gm, 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. (C) 2015 Elsevier Ltd. All rights reserved.