A microscopic study of the creep of a cast TiAl alloy at 750 °C under 150 MPa

The secondary creep stage of a cast duplex Ti48Al48Cr2Nb2 alloy is investigated at 750 °C under 150 MPa. Crept samples are studied by transmission electron microscopy in order to compare the various zones of the alloy microstructure. The deformation microstructure comprises two populations of ordinary dislocations. The same dislocations are observed in equiaxed γ grains and in γ lamellae. The microstructural parameters controlling the creep are looked for and discussed.

► We study the deformation microstructure of a cast duplex TiAl alloy crept in the secondary stage.
► The same ordinary dislocations are observed in the lamellar and single phase zones.
► They can multiply multiply and cross the interfaces.
► The secondary creep is controlled by the mean free path of dislocations, which is given by the lamellae width.