PhD Yindong Fang honored with poster prize at LI CALPHAD conference in 2024 for his work on „Phase equilibria, microsegregations and mechanical properties of Inconel 718 alloy samples processed in electromagnetic levitation facility”
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Publications

PhD Yindong Fang honored with poster prize at LI CALPHAD conference in 2024 for his work on „Phase equilibria, microsegregations and mechanical properties of Inconel 718 alloy samples processed in electromagnetic levitation facility”
Image: L. Tkotz

20 Publikationen filtern

Die Publikationen filtern

Highlighted authors are members of the University of Jena.

  1. Fabrication of shallow EUV gratings on silicon by irradiation with helium ions

    Year of publicationPublished in:Nanotechnology J. Kaufmann, R. Ciesielski, K. Freiberg, M. Walther, A. Fernández Herrero, S. Lippmann, V. Soltwisch, T. Siefke, U. Zeitner
    To accurately achieve structure height differences in the range of single digit nanometres is of great importance for the fabrication of diffraction gratings for the extreme ultraviolet range (EUV). Here, structuring of silicon irradiated through a mask by a broad beam of helium ions with an energy of 30 keV was investigated as an alternative to conventional etching, which offers only limited controllability for shallow structures due to the higher rate of material removal. Utilising a broad ion beam allows for quick and cost effective fabrication. Ion fluence of the irradiations was varied in the range of 10¹⁶ ... 10¹⁷ ions · cm⁻². This enabled a fine tuning of structure height in the range of 1.00 ± 0.05 to 20 ± 1 nm, which is suitable for shallow gratings used in EUV applications. According to transmission electron microscopy investigations the observed structure shape is attributed to the formation of point defects and bubbles/cavities within the silicon. Diffraction capabilities of fabricated elements are experimentally shown at the SX700 beamline of BESSY II. Rigorous Maxwell solver simulation based on the finite-element method and rigorous coupled wave analysis are utilised to describe the experimental obtained diffraction pattern.
    University Bibliography Jena:
    fsu_mods_00023928External link

  2. Comparative Study of Experimental Methods for Measuring Thermal Properties of 100Cr6 Steel Powders

    Year of publicationStatusReview pendingPublished in:Advanced Engineering Materials J. Zhuo, H. Kohl, D. Liu, L. Matthäus, A. Bochmann, A. Berger, S. Weber, S. Nolte, S. Lippmann
    University Bibliography Jena:
    fsu_mods_00025275External link

  3. Climate related phase transitions with moving boundaries by virtue of mushy zone investigation in Al–Cu: Experiment and phase-field modeling

    Year of publicationPublished in:Mathematical Methods in the Applied Sciences I. Nizovtseva, V. Ankudinov, E. Rahner, S. Lippmann
    Studying Arctic ice formation stays in the focus of research groups over the past decades in the context of ice cover changes, thermal budget and climate agenda in general. Nevertheless, the phenomenon's underlying mechanisms are still not completely understood and described. The main reason for the lack in understanding is the limited experimental access to the field data when it comes to the processes that occur below the ice floe. Thus, there is a need to build competent analogies between the natural (ocean water–ice) and laboratory (here: binary alloy) conditions of the experiment as a step of data preparation for the verification of the mathematical model. In the current paper, the existing qualitative models describing the process of melting and crystallization were expanded and the experimental method was developed copying the layering of the natural ocean water–ice mixture. The experimental set-up for studying the solidification within the intermediate zone was designed for Al–Cu alloys being the system with appropriate solidus line for creating a sufficient concentration gradient and by that temperature dependent phase fraction under isothermal conditions. The gained experimental data were used for validating a binary phase-field model for solidification considering moving boundaries. The model includes the description of the free energy of both phases and their respective diffusion coefficients. It allows modeling a binary system at a mesoscopic spatial level by including the concentration-driven phase transition and resolidification in the two-phase region. The novel results will help the quantitative understanding of solidification phenomena and are highly-evaluated from interdisciplinary point of view, including glaciology and geosciences, being ultimately significant for the understanding the global climate change landscape.
    University Bibliography Jena:
    fsu_mods_00010512External link

  4. Dendritic Si growth morphologies in highly undercooled Al–Si alloys

    Year of publicationPublished in:Journal of materials research and technology : official publication of the Brazilian Metallurgical, Materials and Mining Association D. Liu, Y. Fang, S. Nolte, S. Lippmann
    The morphology of primarily crystallizing Si in hypereutectic Al-(20, 40, 55) wt%Si alloys during conventional casting (nucleation undercooling ΔT<1 K) and solidification at high undercoolings (ΔT up to 335 K) has been investigated. As expected, at higher undercoolings a higher nucleation frequency and fast growth of primary Si is observed, leading to the formation of multiple microstructural zones. Instead of the well-known plate-like Si in the as-cast microstructure, various morphologies of primary Si such as faceted and non-faceted blocky morphologies as well as dendrites with aligned side branches showing constant spacing features are observed after solidification at high undercoolings. The special Si dendrites only grow in a limited range of melt concentrations and undercoolings. The transition from faceted to non-faceted growth appears to occur in several steps, as Si dendrites with similar features of the secondary arms as in non-faceted metal alloys are also observed.
    University Bibliography Jena:
    fsu_mods_00013946External link

  5. Volcanic Eruption in the Nanoworld: Efficient Oxygen Exchange at the Si/SnO₂ Interface

    Year of publicationPublished in:Small : nano micro P. Liu, A. Makarova, K. Freiberg, D. Grinter, D. Sharma, P. Ferrer, O. Chuvenkova, T. Deckert-Gaudig, S. Turishchev, S. Lippmann, V. Sivakov
    University Bibliography Jena:
    fsu_mods_00014883External link

  6. Crystalline Microstructure, Microsegregations, and Mechanical Properties of Inconel 718 Alloy Samples Processed in Electromagnetic Levitation Facility

    Year of publicationPublished in:Crystals Y. Fang, C. Yu, N. Kropotin, M. Seyring, K. Freiberg, M. Kolbe, S. Lippmann, P. Galenko
    The solidification of Inconel 718 alloy (IN718) from undercooled liquid is studied. The solidification kinetics is evaluated in melted and undercooled droplets processed using the electromagnetic levitation (EML) technique by the temperature–time profiles and solid/liquid (S/L) interface movement during recalescence. The kinetics is monitored in real time by special pyrometrical measurements and high-speed digital camera. It is shown that the growth velocity of (Formula presented.) -phase (the primary phase in IN718), the final crystalline microstructure (dendritic and grained), and the mechanical properties (microhardness) are strongly dependent on the initial undercooling (Formula presented.) at which the samples started to solidify with the originating (Formula presented.) -phase. Particularly, with the increase in undercooling, the secondary dendrite arm spacing decreases from 28 μm to 5 μm. At small and intermediate ranges of undercooling, the solidified droplets have a dendritic crystalline microstructure. At higher undercooling values reached in the experiment, (Formula presented.) K (namely, for samples solidified with (Formula presented.) K and (Formula presented.) K), fine crystalline grains are observed instead of the dendritic structure of solidified drops. Such change in the crystalline morphology is qualitatively consistent with the behavior of crystal growth kinetics which exhibits the change from the power law to linear law at (Formula presented.) K in the velocity–undercooling relationship (measured by the advancement of the recalescence front in solidifying droplets). Study of the local mechanical properties shows that the microhardness increases with the increase in the (Formula presented.) -phase within interdendritic spacing. The obtained data are the basis for testing the theoretical and computational of multicomponent alloy samples.
    University Bibliography Jena:
    fsu_mods_00011988External link

  7. Non-destructive depth reconstruction of Al-Al₂Cu layer structure with nanometer resolution using extreme ultraviolet coherence tomography

    Year of publicationPublished in:Materials characterization: an international journal on materials structure and behavior J. Abel, J. Apell, F. Wiesner, J. Reinhard, M. Wünsche, N. Felde, G. Schmidl, J. Plentz, G. Paulus, S. Lippmann, S. Fuchs
    Non-destructive cross-sectional characterization of materials systems with a resolution in the nanometer range and the ability to allow for time-resolved in-situ studies is of great importance in material science. Here, we present such a measurements method, extreme ultraviolet coherence tomography (XCT). The method is non-destructive during sample preparation as well as during the measurement, which is distinguished by a negligible thermal load as compared to electron microscopy methods. Laser-generated radiation in the extreme ultraviolet (XUV) and soft x-ray range is used for characterization. The measurement principle is interferometric and the signal evaluation is performed via an iterative Fourier analysis. The method is demonstrated on the metallic material system Al-Al₂Cu and compared to electron and atomic force microscopy measurements. We also present advanced reconstruction methods for XCT, which even allow for the determination of the roughness of outer and inner interfaces.
    University Bibliography Jena:
    fsu_mods_00012595External link

  8. Thermodynamically Guided Improvement of Fe–Mn–Al–Ni Shape-Memory Alloys

    Year of publicationPublished in:Advanced Materials A. Walnsch, A. Bauer, J. Freudenberger, K. Freiberg, C. Wüstefeld, M. Vollmer, S. Lippmann, T. Niendorf, A. Leineweber, M. Kriegel
    A microstructural informed thermodynamic model is utilized to tailor the pseudoelastic performance of a series of Fe–Mn–Al–Ni shape-memory alloys. Following this approach, the influence of the stability and the amount of the B2-ordered precipitates on the stability of the austenitic state and the pseudoelastic response is revealed. This is assessed by a combination of complementary nanoindentation measurements and incremental-strain tests under compressive loading. Based on these investigations, the applicability of the proposed models for the prediction of shape-memory capabilities of Fe–Mn–Al–Ni alloys is confirmed. Eventually, these thermodynamic considerations enable the guided enhancement of functional properties in this alloy system through the direct design of alloy compositions. The procedure proposed renders a significant advancement in the field of shape-memory alloys.
    University Bibliography Jena:
    fsu_mods_00009443External link

  9. Improving Oxidation Resistance of Low Fe-Si Alloys by Preheating Treatment

    Year of publicationPublished in:Metallurgical and Materials Transactions: A, Physical Metallurgy and Materials Science C. Li, W. Ma, Z. Liu, F. Katharina, G. Liu, X. Lang, S. Lippmann, Y. Zhu, Q. Jiang
    In this work, attempts have been made to improve the oxidation resistance of Fe-Si alloys with 0.5, 1.0 and 2.0 mass pct Si by a preheating treatment, which was carried out at 1073 K for 24 hours in high purity hydrogen atmosphere. Compared with pure Fe and untreated Fe-Si alloys, the oxidation resistance of the preheated Fe-Si alloys at 673 K in O₂ is drastically increased, in the case of 2 mass pct Si by two orders of magnitude. The improvement is attributed to a uniform, dense and continuous 25 nm pure SiO₂ layer formed on the alloy surface during the preheating treatment in hydrogen atmosphere hindering the diffusion of Fe and O.
    University Bibliography Jena:
    fsu_mods_00005345External link

  12. Microstructure and Early-Stage Oxidation Behavior of Co-Cr-Cu-Fe-Mn-Ni High-Entropy Alloys

    Year of publicationPublished in:JOM: a journal of the Minerals, Metals & Materials Society J. Apell, R. Wonneberger, M. Pügner, T. Lampke, S. Lippmann, A. Undisz
    The microstructure and early-stage oxidation behavior of the equiatomic CoCrCuFeMnNi high-entropy alloy (HEA) and its six sub-alloys, obtained by omitting one element each, were investigated. Alloys were prepared using induction levitation melting, cold rolled, and oxidized for 1 h at 800°C in air. The Ni-free and Co-free HEAs showed an inhomogeneous microstructure associated with liquid phase separation. The other alloys were either single-phase (Cu-free HEA) or contained two face-centered cubic phases, one Cu-rich and one Cu-poor. The Cu and Mn-containing two-phase alloys showed preferential oxidation of the Cu/Mn-rich phase, leading to Mn-rich oxides that are prone to spallation. The Mn-free alloy exhibited a thicker oxide (~ 5 µm) on the Cu-rich phase, whereas the Cu-poor phase was covered by a thin base oxide (< 1 µm). The single-phase Cu-free (‘Cantor’) alloy formed an approximately 1-µm-thick oxide of the crystal structure types of Mn₃O₄, Mn₂O₃, MnCr₂O₄, and Cr₂O₃. For prospective high-temperature applications, reducing the Cu and Mn content and thus avoiding formation of a second Cu-rich phase is a promising route to facilitate formation of a protective oxide.
    University Bibliography Jena:
    fsu_mods_00007219External link
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