Abstract
Abstract This study examined the influence of Y2O3 addition on the creep behavior of Ti-48Al-2Cr-2Nb alloy. Creep tests of Ti-48Al-2Cr-2Nb and Ti-48Al-2Cr-2Nb-0.05Y2O3 alloys were performed under 275–325 MPa at 800 °C. The results show Y2O3 can significantly enhance the creep properties of the titanium aluminide (TiAl) alloys. Under applied stress, the creep rupture life can be increased three-fold with the addition of Y2O3 and the minimum creep rate drops by around one-third. Stress exponents of the TiAl alloy matrix and Y2O3-bearing alloy were found to be 6.77 and 4.49, respectively, suggesting creep is controlled by the dislocation climb mechanism. The excellent creep properties of the doped alloy can be attributed to the thin lamellar structures and dispersed second phases. The fine Y2O3 particles can impede dislocation climb and prevent sub-boundary formation. Microstructure instabilities occur in both alloys during creep exposure. Y2O3 particles accelerate recrystallization of γ phases and precipitation of B2 phases. The combination of fine grains, increasing massive γ phases and more precipitates in the Y2O3-bearing alloy may promote the development of cracks and cavities, leading to the low fracture strain.
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