Fine-grained fully lamellar (FGFL) structures of XD TiAl alloys (Ti-45 and
47Al-2Nb-2Mn+0.8vol.%TiB2) (at.%) were stabilized to varying degrees by different aging
treatments. Specimens with and without aging were creep tested at 760°C and 207 MPa. It was
found that during creep deformation, degradation of the lamellar structure involving coarsening
within the colonies and spheroidization at colony boundaries occurred, forming fine globular
structures at the colony boundaries and increasing the creep rate. Aging treatments stabilized the
lamellar structure and retarded the coarsening and spheroidization processes during creep
deformation. As a result, the aged specimens exhibited lower minimum creep rates and longer creep
lives than the unaged specimens. A multiple step aging stabilized the lamellar structure to the
greatest extent and suppressed other degradation processes during aging, resulting in the best creep
resistance. These results demonstrate that the multiple step aging is the optimal aging condition for
stabilizing FGFL XD TiAl alloys.
Creep behavior and microstructural evolution of 8030 aluminum alloys compressed at intermediate temperature
