Fractographic Analysis after Creep Testing of Ti-6Al-4V with Yttria and Niobia Co-Doped Zirconia TBC

2025-36-0053

To be published on 12/18/2025

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Abstract
Content
The application of Thermal Barrier Coatings (TBC) has been widely utilized in aerospace turbines to enhance the operational temperature and thermal efficiency of titanium alloys, while preserving their properties such as low density, creep resistance, and corrosion resistance. TBC systems typically consist of a metallic substrate, a metallic coating (Bond Coat), a thermally grown oxide (TGO), and a ceramic topcoat (TC). This study investigated the fracture surface characteristics of Ti-6Al-4V with TBC after a creep test at a constant temperature of 600 °C, under stress levels of 125, 222, and 319 MPa, in order to understand the mechanisms involved. The TBC was composed of a NiCrAlY (BC) and a zirconia co-doped with yttria and nióbia (TC). The fracture characterization of the alloy after the creep test was conducted through stereoscopy and scanning electron microscopy. The fracture mechanism at 600 °C and 222 MPa was predominantly ductile, as evidenced by the presence of dimples and shear zones at the edges of the specimens, indicating necking. In contrast, at 600 °C and stress levels of 125 and 319 MPa, brittle fracture was the dominant mechanism, with cleavage facets and a low percentage of area reduction. Thus, it can be predicted that the titanium alloy with TBC at 600 °C will exhibit better mechanical strength under stress conditions around 222 MPa.
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Citation
Takahashi, Renata Jesuina et al., "Fractographic Analysis after Creep Testing of Ti-6Al-4V with Yttria and Niobia Co-Doped Zirconia TBC," SAE Technical Paper 2025-36-0053, 2025-, .
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Publisher
Published
To be published on Dec 18, 2025
Product Code
2025-36-0053
Content Type
Technical Paper
Language
English