The effect of lamellar spacing on the creep behavior of a fully lamellar TiAl alloy

The compression creep behavior of a cast alloy with the composition of Ti–46Al–2Cr–1.5Nb–1V was studied at 800°C under the stress level of 205 MPa. Different heat treatments were devised to produce fully lamellar microstructures with different lamellar spacings but remaining similar grain sizes, and the effects of the lamellar spacing on the primary creep strain and minimum creep rate of the alloys were investigated. The results indicated that the primary creep strain and minimum creep rate increase with the increase of the lamellar spacing. TEM observation reveals that the multiple generation of dislocation loops from lamellar interfaces contributes to the creep strain. Lamellar interfaces can also act as the barriers to the dislocation motion and multiple generation.