TY - GEN A1 - Gombola, C. A1 - Hasemann, G. A1 - Kauffmann, A. A1 - Sprenger, I. A1 - Laube, S. A1 - Schmitt, A. A1 - Gang, Florian A1 - Bolbut, V. A1 - Oehring, Michael A1 - Blankenburg, Malte A1 - Schell, Norbert A1 - Staron, Peter A1 - Pyczak, Florian A1 - Krüger, Manja A1 - Heilmaier, Martin T1 - A zone melting device for the in-situ observation of directional solidification using high-energy synchrotron X-rays T2 - Review of Scientific Instruments Y1 - 2020 SN - 0034-6748 SN - 1089-7623 VL - 91 IS - 9 ER - TY - GEN A1 - Jin, Bowen A1 - Hejazi, Seyedsina A1 - Pyczak, Florian A1 - Oehring, Michael A1 - Mohajernia, Shiva A1 - Kment, Stepan A1 - Tomanec, Ondrej A1 - Zboril, Radek A1 - Nguyen, Nhat Truong A1 - Yang, Min A1 - Schmuki, Patrik T1 - Amorphous Mo-Ta Oxide Nanotubes for Long-Term Stable Mo Oxide-Based Supercapacitors T2 - ACS Applied Materials and Interfaces Y1 - 2019 SN - 1944-8244 SN - 1944-8252 VL - 11 IS - 49 SP - 45665 EP - 45673 ER - TY - GEN A1 - Wang, Li A1 - Kong, Yi A1 - Oehring, Michael A1 - Song, Min A1 - Pyczak, Florian T1 - Atomic site occupancy of alloying elements and Laves phase stability in γ-γ′ Co-base superalloys T2 - Journal of Alloys and Compounds N2 - The atomic site occupancy of alloying elements in the ZrCo2 and HfCo2 based Laves phases formed in the Co-9Al-9W-2Zr and Co-9Al-9W-2Hf alloys was experimentally determined by the combined techniques of energy-dispersive X-ray spectroscopy mapping with atomic resolution and the atom location by channeling enhanced microanalysis (ALCHEMI) method. The results show that both Al and W occupy the Zr site in the C15 and the Hf site in the C36 crystal structure. The atomic locations of Al and W were further confirmed by comparing calculated inelastic cross-sections with experimental ALCHEMI results. Using the determined atomic site occupancies of alloying elements, special quasirandom structure solid solution models with 192 atoms were constructed and employed in first-principles calculations. It is found theoretically that the energy of formation of the C15 structure is always lower than that of the C36 structure at 0 K in both ZrCo2 and HfCo2 phases, no matter whether Al and W are incorporated or not. However, further ab initio molecular dynamics simulations suggest that lattice vibration at finite temperature contributes significantly to the phase stability, stabilizing the C36 structure compared to the C15 type for the (Hf, Al, W)Co2 phase at finite temperature, which fits well with the experimental findings. Y1 - 2022 U6 - https://doi.org/10.1016/j.jallcom.2022.164261 SN - 1873-4669 SN - 0925-8388 VL - 906 ER - TY - GEN A1 - Wang, Li A1 - Liang, Xiaopeng A1 - Liu, Bin A1 - Oehring, Michael A1 - Paul, Jonathan David Heaton A1 - Liu, Jie A1 - Song, Min A1 - Pyczak, Florian A1 - Liu, Yong T1 - Stacking fault formation in perovskite Ti3AlC carbides in a TiAl based alloy during creep at 800°C T2 - Scripta Materialia Y1 - 2023 U6 - https://doi.org/10.1016/j.scriptamat.2022.115034 SN - 1872-8456 SN - 1359-6462 VL - Vol. 222 ER - TY - GEN A1 - Cao, Xianli A1 - Wang, Li A1 - Tao, Hui A1 - He, Weiwei A1 - Liang, Xiaopeng A1 - Liu, Bin A1 - Oehring, Michael A1 - Paul, Jonathan A1 - Pyczak, Florian A1 - Liu, Yong T1 - Morphology evolution of P-Ti3AlC carbides and their influence on creep properties in a crept Ti-45Al-5Nb-0.75C alloy T2 - Journal of Materials Research and Technology Y1 - 2024 U6 - https://doi.org/10.1016/j.jmrt.2024.02.146 SN - 2238-7854 VL - 29 SP - 4181 EP - 4190 PB - Elsevier BV ER - TY - GEN A1 - Wang, Li A1 - Wang, Yihao A1 - Pyczak, Florian A1 - Oehring, Michael A1 - Song, Min A1 - Liu, Yong T1 - Revealing complex planar defects and their interactions at atomic resolution in a Laves phase containing Co-base superalloy T2 - Acta Materialia Y1 - 2024 U6 - https://doi.org/10.1016/j.actamat.2023.119568 SN - 1359-6454 VL - 264 SP - 1 EP - 20 PB - Elsevier BV ER - TY - GEN A1 - Wang, Li A1 - Wang, Yihao A1 - Liang, Xiaopeng A1 - Liu, Bin A1 - He, Junyang A1 - Oehring, Michael A1 - Pyczak, Florian A1 - Liu, Yong T1 - Revealing the unique evolution and splitting behavior of carbides at atomic-scale in TiAl alloys : the role of elastic interactions and chemical fluctuations T2 - Acta materialia N2 - Cubic perovskite-Ti3AlC carbides are essential strengthening particles in TiAl alloys, especially for application above 800 °C where coarsening is expected to occur. However, these carbides can decompose into small sub-particles upon extended annealing, and the underlying atomic-scale mechanisms, especially structural and compositional changes, driving this unique splitting remain unclear. This study revisits this behavior in a Ti-45Al-5Nb-0.75C alloy utilizing probe-corrected transmission electron microscopy, atom probe tomography and first-principle calculations. The results reveal that the elastic interactions significantly influence carbide evolution. While needle-like carbides transform to intact plates during aging, those in high-density regions tend to coalesce or align along elastically softest γ-matrix directions, forming low-energy plate-like carbide conglomerates. With extended annealing, periodic chemical fluctuations driven by lattice misfit, especially along the needles induce splitting. Simultaneously, a γi-phase with a larger tetragonality and a 90°-rotated c-axis relative to the γ matrix emerges between the sub-particles, which exhibits near-zero lattice mismatch with carbides along [001], combined with mass-center shifts of carbides, further stabilizing the split configurations. This study provides atomic-scale insights into the evolution and stability of strengthening precipitates in systems with tetragonal misfit, and offers new strategies for improving creep properties of TiAl alloys by tailoring carbide configurations. KW - Titanium aluminides KW - Carbides KW - Morphology KW - Elastic interaction KW - STEM HAADF Y1 - 2025 U6 - https://doi.org/10.1016/j.actamat.2025.121277 SN - 1359-6454 VL - 296 SP - 1 EP - 17 PB - Elsevier BV CY - Amsterdam ER -