Internal friction and atomic relaxation processes in an intermetallic Mo-rich Ti-44Al-7Mo (γ+βo) model alloy
| Autor: | J. San Juan, Maria L. Nó, Helmut Clemens, L. Usategui, Svea Mayer |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Materials science Mechanical Engineering Alloy Metallurgy Intermetallic Thermodynamics 02 engineering and technology Activation energy engineering.material 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Crystallographic defect Mechanics of Materials Phase (matter) Vacancy defect 0103 physical sciences engineering Relaxation (physics) General Materials Science Diffusion (business) 0210 nano-technology |
| Zdroj: | Materials Science and Engineering: A. 700:495-502 |
| ISSN: | 0921-5093 |
| Popis: | The design of the next generation of β-stabilized γ-TiAl based alloys as structural materials for high-temperature applications in aircraft engines requires the precise knowledge of the mobility of defects in the ordered β o phase. To reach this goal a Mo-rich prototype alloy has been specifically produced and investigated. The mobility of defects, between 600 K and 1635 K, has been studied by mechanical spectroscopy. The internal friction spectra show a relaxation peak P1 (at 1130 K for 1 Hz) superimposed to a high-temperature background. We demonstrate that the relaxation peak is taking place inside the β o phase and measure an activation energy of E P1 = 3.55 ± 0.05 eV. An atomistic model is additionally proposed to explain this relaxation peak, which is attributed to a Zener-like mechanism of stress-induced Mo-Mo dipoles reorientation by exchange with a vacancy, and consequently the measured activation energy corresponds to the one for Mo diffusion in the β o phase. |
| Databáze: | OpenAIRE |
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