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-4 6Al-2Cr-1.5Nb-1V was studied at 800 degrees C under the stress level of 205 MPa. Different heat treatments were devised to produce fully lamellar micr ostructures with different lamellar spacings bur remaining similar grain si zes, and the effects of the lamellar spacing on the primary creep strain an d minimum creep rate of the alloys were investigated. The results indicated that the primary creep strain and minimum creep rate increase with the inc rease of the lamellar spacing. TEM observation reveals that the multiple ge neration of dislocation loops from lamellar interfaces contributes to the c reep strain. Lamellar interfaces can also act as the barriers to the disloc ation motion and multiple generation. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.