Deformation twinning during the creep of a duplex TiAl alloy was studied. Twinning was already observed, after strains of 0.3%, in γ-phase grains as well as in lamellar grains. The twin formation in lamellar grains was not greatly affected by the present stresses, temperatures and strains. A clear effect was however observed in γ-phase grains, where the interface spacing decreased with increasing strain and stress. Lower temperatures also promoted twinning. Twinning was an easy mode of deformation because of the low stacking-fault energy in near γ-phase alloys.

On the Role of Mechanical Twinning in Creep of a Near-γ TiAl Alloy with Duplex Microstructure B.Skrotzki, M.Unal, G.Eggeler: Scripta Materialia, 1998, 39[8], 1023-9