TY - JOUR A1 - Zaiser, E. A1 - Fantin, Andrea A1 - Manzoni, Anna Maria A1 - Hesse, René A1 - Többens, D. M. A1 - Hsu, W.-C. A1 - Murakami, H. A1 - Yeh, A.-C. A1 - Pavel, M. J. A1 - Weaver, M. L. A1 - Zhu, H. A1 - Wu, Y. A1 - Vogel, F. T1 - Elucidating hierarchical microstructures in high entropy superalloys: An integrated multiscale study N2 - In this study, we examine a high entropy superalloy (HESA-Y1: Ni49.37Co20Cr7Fe4Al11.6Ti6Re1Mo0.5W0.5Hf0.03 at%), focusing on hierarchical microstructure formation and its effects on mechanical properties. Thermodynamic modeling using Thermo-Calc predicts equilibrium phase fractions, compositions, and transition temperatures,which are validated by experimental data from differential scanning calorimetry (DSC). Transmission electronmicroscopy (TEM) reveals that secondary aging induces nanometer-sized γ particles within γ’ precipitates, forming a hierarchical γ/γ’ microstructure. Atom probe tomography (APT) confirms supersaturation of γ’ precipitates with γ-forming elements (Co, Cr, Fe), driving γ particle formation, and measures interfacial widths between γ’ and γ phases. Partitioning coefficients derived from APT align with Thermo-Calc predictions for most elements. Vickers microhardness testing shows an increase of about 50 HV in the hierarchical microstructure compared to the conventional one. In situ synchrotron X-ray diffraction (XRD) from 25 to 750 ◦C determines a small, negative lattice misfit δ between γ and γ’ phases, suggesting enhanced microstructural stability, consistent with Thermo-Calc calculations. Our methodological approach enables measurement of the unconstrained lattice parameter of phase-extracted γ’ in a single-crystal XRD setup. Due to their small size and low volume fraction, γ particles do not produce distinct reflections in the X-ray diffractogram. Elucidating hierarchical microstructures across multiple scales, we establish that the presence of Re and Hf and controlled aging processes lead to enhanced mechanical properties, offering valuable insights for the design of advanced high entropy superalloys. KW - High entropy alloys KW - Transmission electron microscopy KW - X-ray diffraction KW - Superalloy PY - 2025 DO - https://doi.org/10.1016/j.matchar.2024.114642 VL - 220 SP - 1 EP - 13 PB - Elsevier Inc. AN - OPUS4-62348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Li, G. A1 - Koßmehl, G. A1 - Hunnius, W. A1 - Zhu, H. A1 - Plieth, W. A1 - Melsheimer, J. A1 - Doblhofer, K. T1 - Relative groups on polymer coated electrodes - 10. Electrogenerated conducting polyalkylthiophenes bearing activated ester groups N2 - Three new thiophene derivatives containing different activated ester groups covalently attached to the thiophene ring via a linear undecyl spacer have been synthesized. Electropolymerization of these monomers in acetonitrile led to stable electroactive polymers, while activated functional groups withstand the polymerization conditions and were correctly incorporated in the resulting polymers. These polymers show the characteristic electrochemical behavior of poly(3-alkylthiophene)s with the reversible redox transition in the range of 0.7–0.9 V. UV/Vis spectra of them exhibit an absorption maximum at around 460 nm. Conductivity measurements on oxidized films of these polymers by means of the two-probe method gave values in the range of 10-3–10-2 S cm-1. The reactivity of the pendant activated ester groups was demonstrated by the reaction with butylamine, (4-amino-2-oxabutyl) ferrocene and 2-aminoanthraquinone. Spectroscopic studies and electrochemical characterization confirmed that the immobilized amino compounds are covalently bound to the polymer surfaces. These results suggest that the obtained new polymers can be used as electrically conducting carrier materials for the immobilization of biochemically interesting molecules. KW - Conducting polyalkylthiophene KW - Electropolymerization KW - Activated ester PY - 2000 DO - https://doi.org/10.1016/S0032-3861(99)00201-3 SN - 0032-3861 SN - 1873-2291 VL - 41 IS - 2 SP - 423 EP - 432 PB - Springer CY - Berlin AN - OPUS4-884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Li, G. A1 - Koßmehl, G. A1 - Hunnius, W. A1 - Zhu, H. A1 - Plieth, W. A1 - Melsheimer, J. A1 - Doblhofer, K. T1 - Reactive groups on polymer coated electrodes; 10. Electrogenerated conducting polyalkylthiophenes bearing activated ester groups KW - Conducting polyalkylthiophene KW - Electropolymerization KW - Activated ester PY - 1999 SN - 0032-3861 SN - 1873-2291 IS - 41 SP - 423 EP - 432 PB - Springer CY - Berlin AN - OPUS4-776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Li, G. A1 - Koßmehl, G. A1 - Plieth, W. A1 - Melsheimer, J. A1 - Doblhofer, K. A1 - Zhu, H. T1 - New conducting carrier materials: polyalkylthiophene functionalized with 1,2-diol group and its protected forms KW - Polyalkylthiophene KW - Conjugated Polymers KW - New conducting carrier materials PY - 1999 SN - 0323-7648 SN - 1521-4044 IS - 50 SP - 252 EP - 259 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-885 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -