Structure of Ti–Al–Nb intermetallics produced by mechanical alloying and hot-pressing techniques

Mechanical alloying and hot-pressing consolidation were applied for the manufacturing of γ-TiAl alloys with additions of 5, 10 and 15 at.% Nb. The microstructure shows numerous twins within the γ-TiAl phase in the hot-pressed alloys. The grain size (about 0.5 μm) is much smaller than in the cast alloys. Local chemical analysis indicates that Ti is preferentially replaced by Nb in all phases present. The high-resolution microstructure contains regularly spaced dislocations within the α2/γ interface, resulting from a rotation between the {1 1 1}γ and {2 0 1}α2 planes by 2.5°.