High-temperature oxidation behavior of B-modified silicide coatings on Nb–Si based superalloys: Microstructure evolution, failure mechanisms and lifetime prediction
B-modified silicide coatings are widely used to extend the lifetime of Nb–Si based superalloys by protecting them from high temperature oxidation. In this study, B-modified silicide coatings were deposited on Nb–Si based superalloys by pack cementation. The failure behaviors and lifetime prediction...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-09-01
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| Series: | Journal of Materials Research and Technology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785425021052 |
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| Summary: | B-modified silicide coatings are widely used to extend the lifetime of Nb–Si based superalloys by protecting them from high temperature oxidation. In this study, B-modified silicide coatings were deposited on Nb–Si based superalloys by pack cementation. The failure behaviors and lifetime prediction of B-modified silicide coatings under high temperature oxidation conditions were investigated at 1200–1300 °C. The effect of oxidation temperature and interdiffusion behavior on the coating lifetime was addressed. The results confirmed that surface oxidation and interdiffusion between the coating and substrate led to Si depletion in the coating, which subsequently facilitated the formation of the (Ti, Nb)5Si4 phase, accompanied by the formation of numerous voids. The formation of a borosilicate oxide scale on the B-modified silicide coating mitigated surface oxidation. Based on the Boltzmann-Matano theory and Wagner oxidation theory, a life prediction model was established by calculating the oxidation and diffusion activation energies of the coating at high temperatures. The predicted results showed good agreement with the experimental results. |
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| ISSN: | 2238-7854 |