@misc{DinkelHeinzPyczaketal., author = {Dinkel, Michael and Heinz, Paul and Pyczak, Florian and Volek, Andreas and Ott, Michael and Affeldt, Ernst and Vossberg, Andreas and G{\"o}ken, Mathias and Singer, Robert F.}, title = {New Boron and Silicon Free Single Crystal-Diffusion Brazing Alloys}, series = {Superalloys 2008, proceedings of the Eleventh International Symposium on Superalloys, held September 14 - 18, 2008, Pennsylvania, USA}, journal = {Superalloys 2008, proceedings of the Eleventh International Symposium on Superalloys, held September 14 - 18, 2008, Pennsylvania, USA}, editor = {Reed, Roger C. and Green, Kenneth A. and Caron, Pierre and Gabb, Timothy P. and Fahrmann, Michael G. and Huron, Eric S. and Woodard, Shiela R.}, publisher = {TMS}, address = {Warrendale, Pa.}, isbn = {978-0-87339-728-5}, pages = {211 -- 220}, language = {en} } @inproceedings{HeinzVolekSingeretal., author = {Heinz, Paul and Volek, Andreas and Singer, Robert F. and Dinkel, Michael and Pyczak, Florian and G{\"o}ken, Mathias and Ott, Michael and Affeldt, Ernst and Vossberg, Andreas}, title = {Diffusion brazing of single crystalline nickel base superalloys using boron free nickel base braze alloys}, series = {Diffusion in Solids and Liquids III, 3rd International Conference on Diffusion in Solids and Liquids, Liege Konferenz}, booktitle = {Diffusion in Solids and Liquids III, 3rd International Conference on Diffusion in Solids and Liquids, Liege Konferenz}, editor = {{\"O}chsner, Andreas and Murch, Graeme E.}, publisher = {Trans Tech Publ.}, address = {Stafa-Zurich [u.a.]}, isbn = {978-3-908451-51-8}, pages = {294 -- 299}, language = {en} } @inproceedings{DinkelPyczakGoekenetal., author = {Dinkel, Michael and Pyczak, Florian and G{\"o}ken, Mathias and Heinz, Paul and Volek, Andreas and Singer, Robert F. and Ott, Michael and Affeldt, Ernst and Vossberg, Andreas}, title = {Nanoindentation and Orientation Measurements in Single Crystalline Brazing Joints of Nickel-Base Superalloys}, series = {Materials for advanced power engineering 2006, proceedings of the 8th Liege Conference, Bd. 2}, booktitle = {Materials for advanced power engineering 2006, proceedings of the 8th Liege Conference, Bd. 2}, editor = {Lecomte-Beckers, Jacqueline and Carton, M. and Schubert, F. and Ennis, P. J.}, publisher = {Forschungszentrum}, address = {J{\"u}lich}, isbn = {3-89336-436-6}, pages = {633 -- 642}, language = {en} } @misc{BolzOehringLindemannetal., author = {Bolz, Sebastian and Oehring, Michael and Lindemann, Janny and Pyczak, Florian and Paul, Jonathan and Stark, Andreas and Lippmann, Thomas and Roth-Fagaraseanu, Dan and Schreyer, Andreas and Weiß, Sabine and Schr{\"u}fer, Susanne}, title = {Microstructure and mechanical properties of a forged beta-solidifying gamma TiAl alloy in different heat treatment conditions}, series = {Intermetallics}, volume = {2015}, journal = {Intermetallics}, number = {58}, pages = {71 -- 83}, language = {en} } @misc{OehringLindemannPyczaketal., author = {Oehring, Michael and Lindemann, Janny and Pyczak, Florian and Paul, Jonathan and Stark, Andreas and Lippmann, Thomas and Schr{\"u}fer, Susanne and Roth-Fagaraseanu, Dan and Schreyer, Andreas and Weiß, Sabine}, title = {Microstructure and mechanical properties of a forged β-solidifying γ TiAl alloy in different heat treatment conditions}, series = {Intermetallics}, volume = {2015}, journal = {Intermetallics}, number = {58}, issn = {0966-9795}, doi = {10.1016/j.intermet.2014.11.008}, pages = {71 -- 83}, abstract = {In the cast condition g titanium aluminide alloys that solidify completely through the b phase are characterized by fine and homogeneous microstructures, weak textures and low segregation. For these reasons such alloys have a relatively good workability and can be closed-die forged without preceding ingot breakdown even if the alloys contain no large fractions of the b phase at the working temperature. The present work was devoted to a combined study of the constitution and microstructural morphologies that develop in various two-step heat treatments of a single-step forged b solidifying alloy. The study included high-energy X-ray diffraction for in situ investigations of the constitution at the heat treatment temperature. It was observed that the phase ransformations are quite sluggish in the material which results in fine microstructures and some conditions that significantly deviate from thermodynamic equilibrium. Further, tensile and creep testing was carried out on the different material conditions in order to identify the range in which the properties can be varied. It is found that this easily forgeable material exhibits comparable strength, ductility and creep strength as more conventional peritectically solidifying alloys.}, language = {en} } @misc{LiangPaulStarketal., author = {Liang, Zhida and Paul, Jonathan and Stark, Andreas and Bezold, Andreas and Neumeier, Steffen and G{\"o}ken, Mathias and Pyczak, Florian}, title = {High-Temperature CoNi-Based Superalloys Strengthened by γ′-(Ni,Co)3(Cr,Al,Ti,X): The Effect of Refractory Elements}, series = {Metallurgical and materials transactions. A, Physical metallurgy and materials science}, volume = {54 (2023)}, journal = {Metallurgical and materials transactions. A, Physical metallurgy and materials science}, number = {5}, issn = {1543-1940}, doi = {10.1007/s11661-022-06795-y}, pages = {1620 -- 1634}, abstract = {Recent research on Co-based and CoNi-based alloys revealed that the Co-Al-W-system provides interesting properties, however, the high content of W addition triggers high mass density of alloys which limits its industrial application. Therefore, new high temperature superalloys based on the Co-Ni-Al-Ti-system with high content Cr and strengthened by γ′-(Ni,Co)3(Cr,Al,Ti) precipitates, have been developed, and the effect of different refractory element additions was investigated. STEM-EDS and HEXRD were employed to determine the elemental partitioning behavior and the lattice misfit between the γ and γ′ phases. Ta and Nb strongly concentrate within the γ′ phase, whereas Mo weakly partitions to the γ phase. W distributes equally between the γ and γ′ phases. These new superalloys have an unexpectedly high positive misfit compared with some conventional Ni-based superalloys and Co-based superalloys. Nb and Ta additions increase the lattice misfit further, while Mo and W decrease the lattice misfit. The effect of refractory elements alloying on the yield stress at room temperature was evaluated by analyzing the contributions of different strengthening mechanisms. Alloying with Nb or Ta significantly improves precipitation strengthening by increasing the antiphase boundary energy. Mo has the highest solid solution strengthening effect in the γ phase, followed by W. Compared with some conventional Ni-based superalloys, the investigated new CoNi-based superalloys exhibited better mechanical properties at high temperature, which indicates that these compositionally complex alloys are possible candidates for high temperature applications.}, language = {en} } @misc{KaoScheweAkhtaretal., author = {Kao, Ming-Chao and Schewe, Lukas Paul and Akhtar, Arub and Rehm, Jana and Bin Anooz, Saud Bin and Galazka, Zbigniew and Popp, Andreas and Flege, Jan Ingo and Vonk, Vedran and Stierle, Andreas}, title = {Structure and Stability of Al-alloyed β-Ga2O3(100) surfaces}, series = {Verhandlungen der DPG, Berlin 2024}, journal = {Verhandlungen der DPG, Berlin 2024}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {β-Ga2O3 (GaO) holds great promise in high-power applications. GaO is predicted to outperform the leading technologies based on SiC and GaN due to a three times higher calculated critical field strength. It has been identified that alloying with Al results in an almost linear increase in the bandgap between Ga2O3 (4.85eV) and Al2O3 (7eV). A critical issue in the bandgap engineering of GaO is maintaining reasonable electron mobility, which is low for the pure material (150cm2/V/S). This project aims to explore GaO by Al alloying, which allows tunable wide bandgaps for engineering material properties and at the same time maintains excellent crystal quality. PXRD and their Rietveld refinement on several AlGaO crystals indicate a preferential ordering of Al and Ga over octahedral and tetrahedral sites. The results of an SXRD study using synchrotron radiation addressing the surface structure of β-AlxGa2-xO3(100) substrates with x=0-0.25. Our results indicate that the GaO(100) surface is nearly bulk terminated and remains smooth up to 800°C and 10-5mbar of molecular oxygen.}, language = {en} } @misc{KaoScheweAkhtaretal., author = {Kao, Ming-Chao and Schewe, Lukas Paul and Akhtar, Arub and Vlad, Alina and Keller, Thomas F. and Henkel, Karsten and Anooz, Saud Bin and Popp, Andreas and Galazka, Zbigniew and Flege, Jan Ingo and Stierle, Andreas and Vonk, Vedran}, title = {Surface termination of β-Ga₂O₃(100) as-cleaved single crystals}, series = {Applied physics letters}, volume = {128}, journal = {Applied physics letters}, number = {7}, publisher = {AIP Publishing}, address = {Melville, NY}, issn = {0003-6951}, doi = {10.1063/5.0309937}, pages = {1 -- 5}, abstract = {The surface of β-Ga₂O₃ single crystals cleaved along their (100) plane is investigated using surface x-ray diffraction and atomic force microscopy. The results show the surface to consist of a single, so-called B-termination, which means that the crystal cleaves at planes formed by edge-sharing oxygen octahedra, thereby breaking the longest and weakest Ga-O bonds. Refinement of the atomic positions results in small displacements from the bulk structure, at most approximately 0.01 {\AA}. Atomic force microscopy suggests that relatively large terraces form together with steps of half the a-axis length of approximately 0.6 nm, which means that terraces have the same atomic termination, related by the crystal symmetry. These results are important as a fundamental property of β-Ga₂O₃ when processed or used in various semiconductor applications.}, language = {en} } @misc{HoZschechSchmeisseretal., author = {Ho, Paul S. and Zschech, Ehrenfried and Schmeißer, Dieter and Meyer, Moritz Andreas and Huebner, Rene and Hauschildt, Meike and Zhang, Lijuan and Gall, Martin and Kraatz, Matthias}, title = {Scaling effects on microstructure and reliability for cu interconnects}, language = {en} } @misc{MaussNakovWenzeletal., author = {Mauß, Fabian and Nakov, Galin and Wenzel, Paul and Steiner, R{\"u}diger and Kr{\"u}ger, Christian and Zhang, Yongzeh and Rawat, Rajesh and Borg, Andreas and Perlman, Cathleen and Fr{\"o}jd, Karin and Lehtiniemi, Harry}, title = {Soot Simulation under Diesel Engine Conditions Using a Flamelet Approach}, series = {SAE International Journal of Engines}, volume = {2}, journal = {SAE International Journal of Engines}, number = {2}, issn = {1946-3936}, pages = {89 -- 104}, language = {en} } @inproceedings{ChristlGorenzHerzogetal., author = {Christl, Andreas and Gorenz, Paul and Herzog, Nicoleta and Egbers, Christoph}, title = {Eccentric Taylor-Couette Flow with orbital motion of the inner cylinder}, language = {en} }