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- SC16 (4)
- Superalloys (4)
- Creep-deformation (3)
- EXAFS (3)
- Lattice distortion (3)
- Corona (2)
- Creep deformation (2)
- Electron tomography (2)
- GAeF (2)
- High entropy alloys (2)
Organisationseinheit der BAM
- 4 Material und Umwelt (5)
- 4.0 Abteilungsleitung und andere (3)
- 4.2 Material-Mikrobiom Wechselwirkungen (2)
- 5 Werkstofftechnik (2)
- 5.1 Mikrostruktur Design und Degradation (2)
- 6 Materialchemie (1)
- 6.3 Strukturanalytik (1)
- 8 Zerstörungsfreie Prüfung (1)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (1)
High-resolution diffraction using synchrotron x-ray radiation was applied to study γ´ precipitates with an L12 superlattice crystal structure in the single crystal superalloy SC16 after creep deformation at 1223 K with a creep strain of ±0.5% for tensile and compressive loads, respectively. The measurements of full width at half maximum (FWHM) of 001 and 100 γ´ superlattice reflections were performed at various temperatures from ambient temperature to 1173 K in vacuum. The experimental results revealed that the FWHM of both reflections decrease with increasing temperature. It is well-known that changes in particle size and lattice distortion in materials could lead to a variation of FWHM. The observed behaviour is discussed in the light of both the above-mentioned aspects. The decrease in the peak width is mainly attributed to the temperature dependence of the internal strain state.
Specimens of single crystal superalloy SC16 were creep deformed at 1223 K along [0 0 1] up to ±0.5% creep strain using stresses of -150 MPa and +150 MPa, respectively. Line widths and peak positions of superlattice reflections were measured by means of X-ray diffraction parallel and perpendicular to the load axis in the temperature range between 293 K and 1173 K. The line widths were found to decrease with the increase of temperature for both directions on the two specimens after tensile and compressive creep deformation. After both kinds of creep deformation the crystal lattice showed tetragonal distortion which decreased with increasing temperature. The tetragonality after tensile creep deformation was larger than unity while it was smaller than unity after compressive creep deformation. The peak positions and widths restored after cooling back to room temperature. The experimental results can qualitatively be explained by the creation of dislocations during deformation and their anisotropic arrangement at the γ/γ' interfaces.
Time dependence of y/y' Lattice Mismatch in Creep-deformed Single Crystal Superalloy SC16 at 1173 K
(2007)
Local structures of amorphous and quasicrystalline phases in Zr–Ti–Ni and Zr–Ti–Ni–Cu alloys have been studied by means of x-ray absorption spectroscopy. The amorphous phases show a high degree of icosahedral short-range order. In all investigated systems local order around Cu and Ni atoms was found to be nearly identical pointing to site substitution of Ni by Cu as the reason for an improved glass forming ability when Ni is partly substituted by Cu. The results strengthen an icosahedral cluster based approach for the structure of metallic glasses and indicate the importance of the medium-range order on glass formation.