Muñoz-Moreno, RocíoBoehlert, Carl J.Pérez Prado, María TeresaRuiz Navas, Elisa MaríaLlorca, Javier2015-05-122015-05-122012-04Metallurgical and Materials Transactions A (2012). 43(4), 1198-1208.1073-5623 (print)1543-1940 (online)https://hdl.handle.net/10016/20693The deformation and fracture mechanisms of a nearly lamellar Ti-45Al-2Nb-2Mn (at. pct) + 0.8 vol pct TiB₂ intermetallic, processed into an actual low-pressure turbine blade, were examined by means of in situ tensile and tensile-creep experiments performed inside a scanning electron microscope (SEM). Low elongation-to-failure and brittle fracture were observed at room temperature, while the larger elongations-to-failure at high temperature facilitated the observation of the onset and propagation of damage. It was found that the dominant damage mechanisms at high temperature depended on the applied stress level. Interlamellar cracking was observed only above 390 MPa, which suggests that there is a threshold below which this mechanism is inhibited. Failure during creep tests at 250 MPa was controlled by intercolony cracking. The in situ observations demonstrated that the colony boundaries are damage nucleation and propagation sites during tensile creep, and they seem to be the weakest link in the microstructure for the tertiary creep stage. Therefore, it is proposed that interlamellar areas are critical zones for fracture at higher stresses, whereas lower stress, high-temperature creep conditions lead to intercolony cracking and fracture.11application/pdfeng© 2012 The Minerals, Metals & Materials Society and ASM InternationalLamellar tial alloysTitanium aluminide alloysCreep-behaviorFracture mechanismsresearch articleMateriales10.1007/s11661-011-1022-3open access119841208Metallurgical and materials transactions. A, Physical metallurgy and materials science43AR/0000009758