Microstructural Characterization and Analyses of the Damage in a Ti-Based Alloy by X-Ray Computed Microtomography

The microstructural characterization of a fan blade of an aircraft gas turbine, manufacturing of Ti-6Al-4V alloy, was conducted in order to evaluate the occurrence of internal damage. The blade analyzed was removed from aeronautical service. An analysis was carried out by using X-ray computed microtomography and scanning electron microscopy in three samples obtained from the tip and the root of the blade, as well as from its midsection, along its length. These results were compared with those obtained through the microstructural characterization by optical microscopy of specimens, approximately of 15×5×4 mm. The results show the occurrence of early-stage erosive wear on the component and morphological changes of the alpha-grains of Ti-6Al-4V alloy, in comparison with those reported in literature. These changes were observed in the longitudinal and transverse sections of specimens of the blade, which could be related to the mechanical stresses which these elements are subjected during their aeronautical service. The results obtained by X-ray computed microtomography did not show evidence of internal cracking. Finally, the morphological changes identified in the alpha-grains may be a critical parameter to removing these important components from service. Additionally, the use of the open-source software 3D Slicer for the reconstruction of images from X-ray computed microtomography may become a viable and valuable option for the analysis of data obtained by mean of this technique.