Browsing by Author "Guther, V"

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    In and ex situ investigations of the β-phase in a Nb and Mo containing gamma-TiAl based alloy.
    (Elsevier, 2008-06) Clemens, H; Chladil, HF; Wallgram, W; Zickler, GA; Gerling, R; Liss, KD; Kremmer, S; Guther, V; Smarsly, W
    In β-stabilized Ti-43Al-4Nb-1Mo-0.1B alloy (composition in atomic percent) the correlation between the occurrence of β-phase and temperature was analyzed experimentally and compared to thermodynamic calculations. Results from in situ high-energy X-ray diffraction, texture measurements, heat treatments, scanning electron microscopy, and temperature-dependent flow stress measurements were used to study the evolution of the β-phase with temperature. Thermodynamic calculations based on the CALPHAD method were applied to correlate the phases developed in the β-solidifying TiAl based alloy under investigation. This alloy is characterized by an adjustable β-phase volume fraction at temperatures where hot-work processes such as forging and rolling are conducted. Due to a high volume fraction of β-phase at elevated temperatures the hot-extruded alloy can be forged under near conventional conditions. © 2008, Elsevier Ltd.
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    In situ diffraction experiments for the investigation of phase fractions and ordering temperatures in Ti-44 at% Al-(3-7) at% mo alloys
    (Wiley, 2011-04-01) Schmoelzer, T; Mayer, S; Sailer, C; Haupt, F; Guther, V; Staron, P; Liss, KD; Clemens, H
    Being a strong beta stabilizer, Mo has gained importance as an alloying element for so-called beta/gamma-TiAl alloys. Intermetallic TiAl-based alloys which contain a significant volume fraction of the body-centered cubic beta-phase at elevated temperatures have proven to exhibit good processing characteristics during hot-working. Unfortunately, the effect of Mo on the appearing phases and their temperature dependence is not well known. In this work, sections of the Ti-Al-Mo ternary phase diagram derived from thermodynamic calculations as well as experimental data are presented. The phase transition temperatures stated in these phase diagrams are compared with the results of high-temperature diffraction studies using high-energy synchrotron radiation. Additionally, the disordering temperature of the beta(o)-phase is determined. © 1999-2020 John Wiley & Sons, Inc.
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    Phase transition and ordering temperatures of TiAl-Mo alloys investigated by in-situ diffraction experiments
    (Trans Tech Publications, 2010-08-02) Schmoelzer, T; Mayer, S; Haupt, F; Zickler, GA; Sailer, C; Lottermoser, L; Guther, V; Liss, KD; Clemens, H
    Intermetallic TiAl alloys with a significant volume fraction of the body-centered cubic β-phase at elevated temperatures have proven to exhibit good processing characteristics during hot-working. Being a strong β stabilizer, Mo has gained importance as an alloying element for so-called β/γ-TiAl alloys. Unfortunately, the effect of Mo on the appearing phases and their temperature dependence is not well known. In this work, two sections of the Ti-Al-Mo ternary phase diagram derived from experimental data are shown. These diagrams are compared with the results of in-situ high-temperature diffraction experiments using high-energy synchrotron radiation. © 2020 by Trans Tech Publications Ltd.