@inproceedings{StarkSchwaighoferMayeretal., author = {Stark, Andreas and Schwaighofer, Emanuel and Mayer, Svea and Clemens, Helmut and Lippmann, Thomas and Lottermoser, Lars and Schreyer, Andreas and Pyczak, Florian}, title = {In situ high-energy XRD study of the hot-deformation behavior of a novel γ-TiAl alloy}, series = {Intermetallic-based alloys - science, technology and applications, symposium held November 25-30, Boston, Massachusetts, U.S.A}, booktitle = {Intermetallic-based alloys - science, technology and applications, symposium held November 25-30, Boston, Massachusetts, U.S.A}, publisher = {Cambridge Univ. Press}, address = {Cambridge}, doi = {10.1557/opl.2012.1577}, pages = {35 -- 40}, language = {en} } @misc{PyczakBauerGoekenetal., author = {Pyczak, Florian and Bauer, A. and G{\"o}ken, Mathias and Neumeier, Steffen and Lorenz, U. and Oehring, Michael and Schell, N. and Schreyer, Andreas and Stark, Andreas and Szymanzik, F.}, title = {Plastic Deformation Mechanisms in a Crept L12 hardened Co-Base Superalloy}, series = {Materials Science and Engineering A}, journal = {Materials Science and Engineering A}, number = {571}, issn = {1873-4936}, pages = {13 -- 18}, language = {en} } @misc{StarkOehringPyczaketal., author = {Stark, Andreas and Oehring, Michael and Pyczak, Florian and Lippmann, Thomas and Lottermoser, Lars and Schreyer, Andreas}, title = {The transformation mechanism of β phase to ω-related phases in Nb-rich γ-TiAl alloys studied by in situ high-energy X-ray diffraction}, series = {Materials Science Forum}, journal = {Materials Science Forum}, number = {772}, issn = {1662-9752}, pages = {85 -- 89}, language = {en} } @misc{StaronBeckmannLippmannetal., author = {Staron, Peter and Beckmann, Felix and Lippmann, Thomas and Stark, Andreas and Oehring, Michael and Pyczak, Florian and Salgado, Mario and Hort, Norbert and Eckerlebe, Horst and Kainer, Karl Ulrich and M{\"u}ller, Martin and Schreyer, Andreas}, title = {In situ studies of light metals with synchrotron radiation and neutrons}, series = {Materials Science Forum}, journal = {Materials Science Forum}, number = {690}, issn = {1662-9752}, pages = {192 -- 197}, language = {en} } @misc{StarkOehringPyczaketal., author = {Stark, Andreas and Oehring, Michael and Pyczak, Florian and Schreyer, Andreas}, title = {In Situ Observation of Various Phase Transformation Paths in Nb-Rich TiAl Alloys during Quenching with Different Rates}, series = {Advanced Engineering Materials}, volume = {18}, journal = {Advanced Engineering Materials}, number = {8}, issn = {1527-2648}, pages = {700 -- 704}, 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} } @inproceedings{WangPyczakGabrischetal., author = {Wang, Li and Pyczak, Florian and Gabrisch, Heike and Lorenz, Uwe and M{\"u}nch, Mathias and Schimansky, Frank-Peter and Schreyer, Andreas and Stark, Andreas}, title = {Effects of Carbon Content, Annealing Condition and Internal Defects on the nucleation, growth and coarsening of P-type Carbides in High Niobium Containing TiAl Alloys}, series = {Advanced structural and functional intermetallic-based alloys, November 30 - December 5, 2014, Boston, Massachusetts, USA}, booktitle = {Advanced structural and functional intermetallic-based alloys, November 30 - December 5, 2014, Boston, Massachusetts, USA}, publisher = {Curran}, address = {Red Hook, NY}, isbn = {978-1-5108-0634-4}, pages = {61 -- 66}, language = {en} } @inproceedings{RackelStarkGabrischetal., author = {Rackel, Marcus W. and Stark, Andreas and Gabrisch, Heike and Schimansky, Frank-Peter and Schell, Norbert and Schreyer, Andreas and Pyczak, Florian}, title = {In situ synchrotron radiation measurements of orthorhombic phase formation in an advanced TiAl alloy with modulated microstructure}, series = {Advanced structural and functional intermetallic-based alloys, November 30 - December 5, 2014, Boston, Massachusetts, USA}, booktitle = {Advanced structural and functional intermetallic-based alloys, November 30 - December 5, 2014, Boston, Massachusetts, USA}, publisher = {Curran}, address = {Red Hook, NY}, isbn = {978-1-5108-0634-4}, pages = {120 -- 126}, language = {en} } @misc{WangGabrischLorenzetal., author = {Wang, Li and Gabrisch, Heike and Lorenz, Uwe and Schimansky, Frank-Peter and Schreyer, Andreas and Stark, Andreas and Pyczak, Florian}, title = {Nucleation and thermal stability of carbide precipitates in high Nb containing TiAl alloys}, series = {Intermetallics}, volume = {66}, journal = {Intermetallics}, issn = {0966-9795}, doi = {10.1016/j.intermet.2015.07.001}, pages = {111 -- 119}, language = {en} } @misc{StarkRackelTchouahaTankouaetal., author = {Stark, Andreas and Rackel, Marcus W. and Tchouaha Tankoua, Aristide and Oehring, Michael and Schell, Norbert and Lottermoser, Lars and Schreyer, Andreas and Pyczak, Florian}, title = {In situ High-Energy X-Ray Diffraction during Hot-Forming of a Multiphase TiAl Alloy}, series = {Metals}, volume = {5}, journal = {Metals}, number = {4}, issn = {2075-4701}, pages = {2252 -- 2265}, language = {en} } @inproceedings{PyczakRackelGabrischetal., author = {Pyczak, Florian and Rackel, Marcus W. and Gabrisch, Heike and Halici, Dalic and Lorenz, Uwe and Schreyer, Andreas and Stark, Andreas}, title = {In-situ monitoring of thermal treatments and hot deformation of a y-TiAl alloy by high energy X-ray diffraction}, series = {Proceedings of the 1st International Conference on Advanced High-Temperature Materials Technology for Sustainable and Reliable Power Engineering (123HiMAT-2015), June 29 - July 3, 2015, Sapporo, Japan}, booktitle = {Proceedings of the 1st International Conference on Advanced High-Temperature Materials Technology for Sustainable and Reliable Power Engineering (123HiMAT-2015), June 29 - July 3, 2015, Sapporo, Japan}, publisher = {The 123rd Committee of Japan Society for the Promotion of Science, IAI}, address = {Tokyo}, isbn = {978-4-9908874-0-7}, pages = {323 -- 326}, language = {en} } @misc{RackelStarkGabrischetal., author = {Rackel, Marcus W. and Stark, Andreas and Gabrisch, Heike and Schell, Norbert and Schreyer, Andreas and Pyczak, Florian}, title = {Orthorhombic phase formation in a Nb-rich γ-TiAl based alloy - an in situ synchrotron radiation investigation}, series = {Acta Materialia}, volume = {121}, journal = {Acta Materialia}, issn = {1359-6454}, doi = {10.1016/j.actamat.2016.09.030}, pages = {343 -- 351}, language = {en} } @misc{LaippleStarkSchimanskyetal., author = {Laipple, Daniel and Stark, Andreas and Schimansky, Frank-Peter and Schwebke, Bernd and Pyczak, Florian and Schreyer, Andreas}, title = {Microstructure of Ti-45Al-5Nb and Ti-45Al-10Nb powders}, series = {Key Engineering Materials}, volume = {704}, journal = {Key Engineering Materials}, issn = {1662-9795}, doi = {10.4028/www.scientific.net/KEM.704.214}, pages = {214 -- 222}, language = {en} } @misc{FreundStarkKirchmayeretal., author = {Freund, Lisa P. and Stark, Andreas and Kirchmayer, Andreas and Schell, Norbert and Pyczak, Florian and G{\"o}ken, Mathias and Neumeier, Steffen}, title = {The Effect of a Grain Boundary Pinning B2 Phase on Polycrystalline Co-Based Superalloys with Reduced Density}, series = {Metallurgical and Materials Transactions A}, volume = {49}, journal = {Metallurgical and Materials Transactions A}, number = {9}, issn = {1543-1940}, doi = {10.1007/s11661-018-4757-2}, pages = {4070 -- 4078}, 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{OehringStarkPauletal., author = {Oehring, Michael and Stark, Andreas and Paul, Jonathan David Heaton and Lippmann, Thomas and Pyczak, Florian}, title = {Microstructural refinement of boron-containing β-solidifying γ-titanium aluminide alloys through heat treatments in the β phase field}, series = {Intermetallics}, journal = {Intermetallics}, number = {32}, isbn = {0966-9795}, pages = {12 -- 20}, language = {en} } @misc{SchlofferIqbalGabrischetal., author = {Schloffer, Martin and Iqbal, Farasat and Gabrisch, Heike and Schwaighofer, Emanuel and Schimansky, Frank-Peter and Mayer, Svea and Stark, Andreas and Lippmann, Thomas and G{\"o}ken, Mathias and Pyczak, Florian and Clemens, Helmut}, title = {Microstructure development and hardness of a powder metallurgical multi phase gamma-TiAl based alloy}, series = {Intermetallics}, journal = {Intermetallics}, number = {22}, issn = {0966-9795}, doi = {10.1016/j.intermet.2011.11.015}, pages = {231 -- 240}, language = {en} } @inproceedings{HauschildtStarkLorenzetal., author = {Hauschildt, Katja and Stark, Andreas and Lorenz, Uwe and Schell, Norbert and Fischer, Torben and Blankenburg, Malte and M{\"u}ller, Martin and Pyczak, Florian}, title = {Diffusion brazing of γ-TiAl-alloys: Investigations of the joint by electron microscopy and high-energy X-ray diffraction}, series = {Intermetallic-based alloys - science, technology and applications, symposium held November 25-30, Boston, Massachusetts, U.S.A}, booktitle = {Intermetallic-based alloys - science, technology and applications, symposium held November 25-30, Boston, Massachusetts, U.S.A}, publisher = {Cambridge Univ. Press}, address = {Cambridge}, doi = {10.1557/opl.2012.1750}, pages = {215 -- 220}, language = {en} } @misc{GabrischStarkSchimanskyetal., author = {Gabrisch, Heike and Stark, Andreas and Schimansky, Frank-Peter and Wang, Li and Schell, Norbert and Pyczak, Florian}, title = {Carbides in Ti-45Al-5Nb alloys with different carbon contents}, series = {Intermetallics}, journal = {Intermetallics}, number = {33}, issn = {0966-9795}, pages = {44 -- 53}, language = {en} } @inproceedings{GabrischLorenzOehringetal., author = {Gabrisch, Heike and Lorenz, Uwe and Oehring, Michael and Paul, Jonathan and Pyczak, Florian and Rackel, Marcus W. and Schimansky, Frank-Peter and Stark, Andreas}, title = {TiAlNb-alloy with a modulated B19 containing constituent produced by powder metallurgy}, series = {Intermetallic-based alloys - science, technology and applications, symposium held November 25-30, Boston, Massachusetts, U.S.A}, booktitle = {Intermetallic-based alloys - science, technology and applications, symposium held November 25-30, Boston, Massachusetts, U.S.A}, publisher = {Cambridge Univ. Press}, address = {Cambridge}, doi = {10.1557/opl.2012.1575}, pages = {35 -- 40}, language = {en} } @inproceedings{StarkOehringPyczak, author = {Stark, Andreas and Oehring, Michael and Pyczak, Florian}, title = {Influence of Quenching Rates on the Transformation of Ternary Phases in Nb-rich γ-TiAl Alloys}, series = {Intermetallic-based alloys for structural and functional applications, symposium held November 29 - December 3, Boston, Massachusetts, U.S.A}, booktitle = {Intermetallic-based alloys for structural and functional applications, symposium held November 29 - December 3, Boston, Massachusetts, U.S.A}, editor = {Palm, Martin and Bewlay, Bernard P. and Kumar, K. Sharvan and Yoshimi, Kyosuke}, publisher = {Cambridge Univ. Press}, address = {Cambridge}, doi = {doi:10.1557/opl.2011.30}, pages = {107 -- 112}, language = {en} } @misc{TchouahaTankouaStarkRackeletal., author = {Tchouaha Tankoua, Aristide and Stark, Andreas and Rackel, Marcus W. and Pyczak, Florian and Hehl, Axel von}, title = {In situ analysis of the forging process of a novel γ-TiAl alloy using synchrotron radiation}, series = {Materialwissenschaft und Werkstofftechnik}, volume = {47}, journal = {Materialwissenschaft und Werkstofftechnik}, number = {11}, issn = {1521-4052}, doi = {10.1002/mawe.201600635}, pages = {1109 -- 1120}, language = {en} } @misc{WangLorenzMuenchetal., author = {Wang, Li and Lorenz, Uwe and M{\"u}nch, Mathias and Stark, Andreas and Pyczak, Florian}, title = {Influence of alloy composition and thermal history on carbide precipitation in γ-based TiAl alloys}, series = {Intermetallics}, volume = {89}, journal = {Intermetallics}, issn = {0966-9795}, pages = {32 -- 39}, language = {en} } @misc{GabrischLorenzPyczaketal., author = {Gabrisch, Heike and Lorenz, Uwe and Pyczak, Florian and Rackel, Marcus W. and Stark, Andreas}, title = {Morphology and stability of orthorhombic and hexagonal phases in a lamellar γ-Ti-42Al-8.5Nb alloy-A transmission electron microscopy study}, series = {Acta Materialia}, volume = {135}, journal = {Acta Materialia}, issn = {1359-6454}, pages = {304 -- 313}, language = {en} } @misc{WangZenkStarketal., author = {Wang, Li and Zenk, Carolin and Stark, Andreas and Felfer, Peter and Gabrisch, Heike and G{\"o}ken, Mathias and Lorenz, Uwe and Pyczak, Florian}, title = {Morphology evolution of Ti3AlC carbide precipitates in high Nb containing TiAl alloys}, series = {Acta Materialia}, journal = {Acta Materialia}, number = {137}, issn = {1359-6454}, pages = {36 -- 44}, language = {en} } @misc{LazurenkoBataevMalietal., author = {Lazurenko, Daria V. and Bataev, Ivan A. and Mali, Vyacheslav I. and Jorge, J. R. and Stark, Andreas and Pyczak, Florian and Ogneva, T. S. and Maliutina, I. N.}, title = {Synthesis of metal-intermetallic laminate (MIL) composites with modified Al3Ti structure and in situ synchrotron X-ray diffraction analysis of sintering process}, series = {Materials and Design}, volume = {151}, journal = {Materials and Design}, issn = {0264-1275}, doi = {10.1016/j.matdes.2018.04.038}, pages = {8 -- 16}, language = {en} } @misc{FreundStarkPyczaketal., author = {Freund, Lisa P. and Stark, Andreas and Pyczak, Florian and Schell, Norbert and G{\"o}ken, Mathias and Neumeier, Steffen}, title = {The grain boundary pinning effect of the µ phase in an advanced polycrystalline γ/γʹ Co-base superalloy}, series = {Journal of Alloys and Compounds}, volume = {753}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2018.04.204}, pages = {333 -- 342}, language = {en} } @misc{WangOehringLorenzetal., author = {Wang, Li and Oehring, Michael and Lorenz, Uwe and Stark, Andreas and Pyczak, Florian}, title = {New insights into perovskite-Ti3AlC precipitate splitting in a Ti-45Al-5Nb-0.75C alloy by transmission electron microscopy}, series = {Intermetallics}, volume = {100}, journal = {Intermetallics}, issn = {0966-9795}, doi = {10.1016/j.intermet.2018.06.006}, pages = {70 -- 76}, language = {en} } @misc{LazurenkoStarkEsikovetal., author = {Lazurenko, Daria V. and Stark, Andreas and Esikov, Maksim A. and Paul, Jonathan and Bataev, Ivan A. and Kashimbetova, Adelya A. and Mali, Vyacheslav I. and Lorenz, Uwe and Pyczak, Florian}, title = {Ceramic-Reinforced γ-TiAl-Based Composites: Synthesis, Structure, and Properties}, series = {Materials}, volume = {12}, journal = {Materials}, number = {4}, issn = {1996-1944}, doi = {10.3390/ma12040629}, pages = {20}, language = {en} } @misc{WangSongStarketal., author = {Wang, Li and Song, Lin and Stark, Andreas and Liu, Yong and Oehring, Michael and Lorenz, Uwe and Pyczak, Florian}, title = {Identification of Laves phases in a Zr or Hf containing γ-γ′ Co-base superalloy}, series = {Journal of Alloys and Compounds}, volume = {805}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, pages = {880 -- 886}, language = {en} } @misc{SongHuWangetal., author = {Song, Lin and Hu, Xingguo and Wang, Li and Stark, Andreas and Lazurenko, Daria V. and Lorenz, Uwe and Lin, Junpin and Pyczak, Florian and Zhang, Tiebang}, title = {Microstructure evolution and enhanced creep property of a high Nb containing TiAl alloy with carbon addition}, series = {Journal of Alloys and Compounds}, volume = {807}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2019.151649}, pages = {11}, language = {en} } @misc{HauschildtStarkSchelletal., author = {Hauschildt, Katja and Stark, Andreas and Schell, Norbert and M{\"u}ller, Martin and Pyczak, Florian}, title = {The transient liquid phase bonding process of a γ-TiAl alloy with brazing solders containing Fe or Ni}, series = {Intermetallics}, volume = {106}, journal = {Intermetallics}, issn = {0966-9795}, pages = {48 -- 58}, language = {en} } @misc{WangOehringLietal., author = {Wang, Li and Oehring, Michael and Li, Yuzhi and Song, Lin and Liu, Yon and Stark, Andreas and Lorenz, Uwe and Pyczak, Florian}, title = {Microstructure, phase stability and element partitioning of γ/γʹ Co-9Al-9W-2X alloys in different annealing conditions}, series = {Journal of Alloys and Compounds}, volume = {787}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, pages = {594 -- 605}, language = {en} } @misc{LiPyczakStarketal., author = {Li, Yuzhi and Pyczak, Florian and Stark, Andreas and Wang, Li and Oehring, Michael and Paul, Jonathan and Lorenz, Uwe}, title = {Temperature dependence of misfit in different Co-Al-W ternary alloys measured by synchrotron X-ray diffraction}, series = {Journal of Alloys and Compounds}, volume = {819}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, pages = {9}, language = {en} } @misc{SongAppelWangetal., author = {Song, Lin and Appel, Fritz and Wang, Li and Oehring, Michael and Hu, Xingguo and Stark, Andreas and He, Junyang and Lorenz, Uwe and Zhang, Tiebang and Lin, Junpin and Pyczak, Florian}, title = {New insights into high-temperature deformation and phase transformation mechanisms of lamellar structures in high Nb-containing TiAl alloys}, series = {Acta Materialia}, volume = {186}, journal = {Acta Materialia}, issn = {1873-2453}, doi = {10.1016/j.actamat.2020.01.021}, pages = {575 -- 586}, language = {en} } @misc{LazurenkoLaptevGolkovskyetal., author = {Lazurenko, Daria V. and Laptev, Ilia S. and Golkovsky, Mikhail G. and Stark, Andreas and Paul, Jonathan and Bataev, Ivan A. and Ruktuev, Alexey A. and Song, Lin and Gollwitzer, Christian and Pyczak, Florian}, title = {Influence of the Ti/Al/Nb ratio on the structure and properties on intermetallic layers obtained on titanium by non-vacuum electron beam cladding}, series = {Materials Characterization}, volume = {163}, journal = {Materials Characterization}, issn = {1044-5803}, pages = {13}, language = {en} } @misc{IvanovLazurenkoStarketal., author = {Ivanov, Ivan V. and Lazurenko, Daria V. and Stark, Andreas and Pyczak, Florian and Th{\"o}mmes, Alexander and Bataev, Ivan A.}, title = {Application of Different Diffraction Peak Profile Analysis Methods to Study the Structure Evolution of Cold-Rolled Hexagonal α-Titanium}, series = {Metals and Materials International}, volume = {26}, journal = {Metals and Materials International}, number = {1}, issn = {2005-4149}, doi = {10.1007/s12540-019-00309-z}, pages = {83 -- 93}, language = {en} } @misc{LiuSongStarketal., author = {Liu, Xu and Song, Lin and Stark, Andreas and Lorenz, Uwe and He, Zhanbing and Lin, Junpin and Pyczak, Florian and Zhang, Tiebang}, title = {Deformation and phase transformation behaviors of a high Nb-containing TiAl alloy compressed at intermediate temperatures}, series = {Journal of Materials Science and Technology}, volume = {102}, journal = {Journal of Materials Science and Technology}, issn = {0861-9786}, doi = {10.1016/j.jmst.2021.06.041}, pages = {89 -- 96}, abstract = {In modern β-solidified TiAl alloys, the decomposition of α2 phase is frequently observed during heat treatment or high-temperature deformation of the alloys. In this study, high-temperature deformation and decomposition mechanisms of α2 phase in a Ti-45Al-8.5Nb-0.2B-0.2W-0.02Y alloy are investigated. In a sample deformed at 800 °C, the precipitation of βo(ωo) phase is observed within the equiaxed α2 phase. The nucleation of ωo particles within the βo matrix indicates the α2→βo→ωo transformation. In addition, numerous γ phase precipitates form within the βo(ω) areas. The α2 lamellae decompose into ultrafine (α2+γ) lamellae and coarsened γ lamellae via α2→α2+γ and α2→γ transformation, respectively. Moreover, the ωo phase nucleates within the ultrafine lamellae via α2→ωo transformation. However, in a sample deformed at 1000 °C, the nucleation of βo particles is sluggish, which is caused by the efficient release of the internal stress via dynamic recrystallization (DRX). These results indicate that complex phase transformations can be introduced by the decomposition of α2 phase in TiAl alloys with a high amount of β-stabilizing elements.}, language = {en} } @misc{LazurenkoPetrovMalietal., author = {Lazurenko, Daria V. and Petrov, Ivan Yu and Mali, Vyacheslav I. and Esikov, Maksim A. and Kuzmin, R. I. and Lozanov, V. V. and Pyczak, Florian and Stark, Andreas and Dovzhenko, G. D. and Bataev, Ivan A. and Terentiev, D. S. and Ruktuev, Alexey A.}, title = {Ti-Al3Ti metal-intermetallic laminate (MIL) composite with a cubic titanium trialuminide stabilized with silver: Selection of fabrication regimes, structure, and properties}, series = {Journal of Alloys and Compounds}, volume = {916}, journal = {Journal of Alloys and Compounds}, issn = {1873-4669}, doi = {10.1016/j.jallcom.2022.165480}, abstract = {Ti-Al3Ti metal-intermetallic laminate (MIL) composites are known as promising structural materials due to the unique combination of their specific properties. However, their application is still limited due to the extremely high brittleness of the Al3Ti phase. In this study, we attempt to address this issue by changing the D022 crystal structure of Al3Ti to the more ductile L12 structure by alloying it with silver. To select the best fabrication regimes of Ti-Ti(Al1-xAgx)3 composites, in situ synchrotron X-ray diffraction analysis was performed to reveal the chemical reactions occurring upon heating the Ti-Al-Ag sample. The analysis showed that the highest amount of Ti(Al1-xAgx)3 phase with the L12 structure appears at 930 °C. This temperature was chosen for subsequent spark plasma sintering experiments. Scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction analysis revealed that the sintered sample consisted mainly of Ti, Ti(Al1-xAgx)3, and a minor fraction of the Ag-Al compound distributed in the central parts of the intermetallic layers and at the grain boundaries. Modification of the titanium trialuminide crystal structure positively affected the properties of the composite, providing a 60\% increase in fracture toughness. The Ag-Al phase also contributed to toughening, causing an additional crack deflection effect.}, language = {en} } @misc{LiuSongLiuetal., author = {Liu, Xu and Song, Lin and Liu, Tong and Stark, Andreas and Pyczak, Florian and He, Zhanbing and Lin, Junpin and Zhang, Tiebang}, title = {In- and ex-situ study of the deformation behavior of the βo(ωo) phase in a Ti4Al3Nb alloy during high-temperature compression}, series = {Journal of Alloys and Compounds}, volume = {918}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2022.165626}, abstract = {In-situ synchrotron-based high energy X-ray diffraction (HEXRD) and ex-situ Gleeble tests were conducted to investigate the deformation behavior of the βo(ωo) phase in a Ti4Al3Nb alloy. In samples compressed at 600 and 800 °C, the brittle ωo phase deforms mostly elastically, resulting in the failure of the Ti4Al3Nb alloy by premature fracture. In a sample deformed at 900 °C, the ωo phase mostly transforms into the βo phase under uniaxial loading. Moreover, the ductility of a Ti4Al3Nb alloy is largely enhanced at this temperature. In a sample deformed at 1000 °C, dynamic recrystallization (DRX) of the βo phase extensively takes place. Direction 1 (D1) and Direction 2 (D2) deviating from the loading direction with an angle of 65° ± 5° and 15° ± 5° are selected to analyze the lattice strain evolution of (110)βo lattice planes. At the late stage of macro strain hardening, deformed[removed]βo//D1 oriented grains bear a higher load due to the occurrence of DRX in[removed]βo//D2 oriented grains. Subsequently, DRX continues in[removed]βo//D1 oriented βo grains. The coordinated deformation of βo grains ensures the good deformability of a Ti4Al3Nb alloy at 1000 °C.}, language = {en} } @misc{GabrischJanovskaRackeletal., author = {Gabrisch, Heike and Janovsk{\´a}, Michaela and Rackel, Marcus W. and Pyczak, Florian and Stark, Andreas}, title = {Impact of microstructure on elastic properties in the alloy Ti-42Al-8.5 Nb}, series = {Journal of Alloys and Compounds}, volume = {Vol. 932}, journal = {Journal of Alloys and Compounds}, issn = {1873-4669}, doi = {10.1016/j.jallcom.2022.167578}, language = {en} } @misc{LiuStarkPyczaketal., author = {Liu, Xu and Stark, Andreas and Pyczak, Florian and Zhang, Tiebang}, title = {In-situ synchrotron high energy X-ray diffraction study on the internal strain evolution of D019-α2 phase during high-temperature compression and subsequent annealing in a TiAl alloy}, series = {Journal of Materials Science and Technology}, volume = {Vol. 163}, journal = {Journal of Materials Science and Technology}, issn = {1941-1162}, doi = {10.1016/j.jmst.2023.04.027}, pages = {212 -- 222}, language = {en} } @misc{FroebelStarkPauletal., author = {Fr{\"o}bel, Ulrich and Stark, Andreas and Paul, Jonathan and Pyczak, Florian}, title = {Assessment of the capability of Zr, Y, La, Gd, Dy, C, and Si to enhance the creep strength of gamma titanium aluminide alloys based on their effect on flow stress and thermal activation parameters}, series = {Intermetallics}, volume = {Vol. 162}, journal = {Intermetallics}, issn = {1879-0216}, doi = {10.1016/j.intermet.2023.108018}, language = {en} } @misc{GussoneRackelTumminelloetal., author = {Gussone, Joachim and Rackel, Marcus W. and Tumminello, Silvana and Barriobero-Vila, Pere and Kreps, Frederic and Kelm, Klemens and Stark, Andreas and Schell, Norbert and Pyczak, Florian and Haubrich, Jan and Requena, Guillermo}, title = {Microstructure formation during laser powder bed fusion of Ti-22Al-25Nb with low and high pre-heating temperatures}, series = {Materials and Design}, volume = {Vol. 232}, journal = {Materials and Design}, issn = {0264-1275}, doi = {10.1016/j.matdes.2023.112154}, language = {en} } @misc{GuoSongLiuetal., author = {Guo, Xiang and Song, Lin and Liu, Xu and Stark, Andreas and Pyczak, Florian and Zhang, Tiebang}, title = {In-situ synchrotron HEXRD study on the phase transformation mechanisms of the ω-related phases in a Ti4Al3Nb alloy}, series = {Materials Characterization}, volume = {Vol. 200}, journal = {Materials Characterization}, issn = {1873-4189}, doi = {10.1016/j.matchar.2023.112901}, language = {en} } @misc{LiuSongStarketal., author = {Liu, Xu and Song, Lin and Stark, Andreas and Pyczak, Florian and Zhang, Tiebang}, title = {In-situ synchrotron high energy X-ray diffraction study on the deformation mechanisms of D019-α2 phase during high-temperature compression in a TiAl alloy}, series = {Journal of Materials Research and Technology}, volume = {33}, journal = {Journal of Materials Research and Technology}, publisher = {Elsevier BV}, issn = {2238-7854}, doi = {10.1016/j.jmrt.2024.10.231}, pages = {5850 -- 5862}, language = {en} } @misc{LiuSongPyczaketal., author = {Liu, Xu and Song, Lin and Pyczak, Florian and Stark, Andreas and Wang, Li and Guo, Xiang and Zhang, Tiebang}, title = {Stress-induced orthorhombic O phase in TiAl alloys}, series = {Acta materialia}, volume = {286}, journal = {Acta materialia}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {1359-6454}, doi = {10.1016/j.actamat.2025.120751}, pages = {1 -- 13}, abstract = {The orthorhombic O phase precipitation within the D019-α2 phase has attracted increasing attention recently in high Nb containing TiAl (high Nb-TiAl) alloys since the precipitation temperature is close to the expected service temperature of the alloys. In this study, in-situ synchrotron high energy X-ray diffraction (HEXRD) reveals that the O phase precipitates at 550 °C while it dissolves into the α2 phase at 750 °C during heat treatments. However, under external stress the O phase unexpectedly precipitates from α2 phase at 800 °C and even 900 °C. The O phase formation proceeds further in the presence of a critical stress promoted by internal stress accumulation in the α2 phase, whereas the reverse O→α2 phase transformation takes place when the internal stresses are relaxed. Additionally, it has been revealed that the O phase preferentially precipitates from specifically oriented α2 grains with one of their <110> directions aligned perpendicular and their 〈0001〉 directions rotated by an angle of 120° out of the external load axis. This α2 phase orientation facilitates the α2→O crystal transition during uniaxial compression. Transmission electron microscopy (TEM) study shows that stress-induced α2→O transformation is governed by small atomic shifts in the α2 lattice. In addition, the selective growth of certain O variants via shuffling along an [110]α2 direction is found to accommodate the external strain component in this direction.}, language = {en} } @misc{StarkRackelPyczak, author = {Stark, Andreas and Rackel, Marcus W. and Pyczak, Florian}, title = {How rapid heating and quenching cycles affect phase evolution in advanced γ-TiAl alloys : an in situ synchrotron radiation study}, series = {MRS communications}, volume = {15}, journal = {MRS communications}, number = {4}, publisher = {Springer Science and Business Media LLC}, address = {Berlin}, issn = {2159-6867}, doi = {10.1557/s43579-025-00756-3}, pages = {790 -- 795}, abstract = {Additive manufacturing (AM) processes are increasingly considered as an alternative manufacturing route to produce complex aircraft components out of γ-TiAl-based alloys. Due to the process-related high and short-time energy input, extremely fast heating and cooling rates occur which can result in thermodynamic and chemical disequilibrium. We studied the effect of rapid heating and quenching cycles in a Ti-48Al-2Nb-2Cr (in at.\%) alloy by carrying out in situ high-energy X-ray diffraction experiments in which AM-related heating cycles were simulated. These in situ experiments allow to determine the influence of cooling rate and a chosen powder bed temperature on phase evolution.}, language = {en} } @misc{StarkLottPyczak, author = {Stark, Andreas and Lott, Dieter and Pyczak, Florian}, title = {A dilatometer and in situ synchrotron X-ray diffraction study : α-quenching and reheating of a Nb-rich titanium aluminide alloy}, series = {MRS advances}, volume = {10}, journal = {MRS advances}, number = {14}, publisher = {Springer Science and Business Media LLC}, address = {Cham}, issn = {2731-5894}, doi = {10.1557/s43580-025-01382-w}, pages = {1767 -- 1772}, abstract = {Intermetallic γ-TiAl-based alloys are currently used as structural materials for turbine blades in aero engines. Additive manufacturing is increasingly considered as an additional manufacturing route for components consisting of γ titanium aluminides; however, the high heating and cooling rates result in chemical and thermodynamical disequilibrated microstructures. In our study, in situ synchrotron X-ray diffraction was applied to follow the formation of the disequilibrium microstructure during quenching and to study its re-equilibration during a subsequent annealing treatment in a Nb-rich γ-TiAl-based alloy. The quenched sample showed an incomplete massive transformation, with large remaining α2 grains. During reheating, the analysis of the collected data showed that equilibration of the quenched microstructure takes place in several reordering and transformation steps, e.g., orthorhombic distortion of the hexagonal α2 phase (around 550 °C), almost complete transformation of the supersaturated quenched α2 to γ (around 850 °C), and retransformation of γ to new α2 (around 1050 °C).}, language = {en} } @misc{LiuLiuWuetal., author = {Liu, Shen and Liu, Xu and Wu, Qiaohan and Li, Yixuan and Shi, Qiuyi and Song, Lin and Pyczak, Florian and Stark, Andreas and Li, Xiaobing and Zhang, Tiebang}, title = {In-situ synchrotron high energy X-ray diffraction study on the internal strain evolution of an extruded Ti-45Al-8Nb-0.2C alloy during high-temperature compression}, series = {Materials characterization}, volume = {230}, journal = {Materials characterization}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {1044-5803}, doi = {10.1016/j.matchar.2025.115746}, pages = {1 -- 12}, abstract = {Due to their exceptional properties, γ-TiAl based alloys present substantial prospect for aerospace and automotive applications. However, the significant disparity in plasticity between the D019-α2 and L10-γ phases greatly affects TiAl alloys' service behavior. This study investigates the internal strain accumulation in the α2 and γ phases of an extruded Ti-45Al-8Nb-0.2C alloy during compression at 900 °C and the subsequent stress relaxation behavior during annealing at 850 °C, using in situ synchrotron high-energy X-ray diffraction (HEXRD). During compression, the γ phase starts to yield plastically at approximately 410 MPa true stress, progressively shifting the load to the α2 phase and generating high residual stress in the α2 phase after deformation. However, annealing at 850 °C for 30 min only partially relieves the residual stress in the α2 phase, with the relaxation rate decreasing substantially after the first 10 min. Furthermore, when the true stress reaches 790 MPa during compression, the α2 phase undergoes rigid-body rotation to accommodate the plastic deformation of the adjacent γ phase, initiating texture evolution that ultimately forms a distinct fiber texture.}, language = {en} }