EFFECTS OF LAMELLAR SPACING ON THE CREEP BEHAVIOR OF A CAST TiAl ALLOY WITH FULLY LAMELLAR STRUCTURE

Fully lamellar microstructures of TiAl alloy with the identical grain sizes and three different lamellar spacings were obtained by the different heat treatment, and the effects of the lamellar spacing on the creep behavior of the TiAl alloy with fully lamellar microstructures were investigated at the conditions of T=800℃ , σ=205MPa. The results showed that the primary creep and minimum creep rate increased with the increase of the lamellar spacing. Dislocations can be detached from the lamellar interfaces and thus contribute to the creep deformation, and, on the other hand, the interfaces can inhibit the multiple generation of dislocation loops and restrict their motion.