@misc{KathoeferPyczak, author = {Kath{\"o}fer, Fabian and Pyczak, Florian}, title = {Effect of ternary elements on the eutectic temperature and microstructure in TiAl-x (x=Nb,Cr,Zr), MSE, Darmstadt, 2018}, pages = {1}, abstract = {Titanium aluminides alloys (TiAl) based on the intermetallic γ-phase are widely recognized for their potential as aero engine components. This is due to their comparable service temperature and lower density than conventional metallic systems as for example Ni-base superalloys. For this reason, TiAl alloys are recently used in aircraft turbines as material for turbine blades. However, on the alloying development side almost exclusively the processing of cast or forged parts is state of art. Also, the forming of these alloys is still challenging and expensive, since the necessary forming temperatures between 1100 °C and 1250 °C bring currently available die materials to their limits. The present research is focused on the modification of TiAl-X (X being a ternary alloying element) alloy compositions to create a phase constitution that allows isothermal forming at lower temperatures. The underlying idea is to stabilize the unordered α-phase in the temperature regime between 1000 - 1100°C. It is expected that this unordered α-phase can be deformed more easily than ordered phases α2 and γ normally present in TiAl alloys. Based on the work of Kainuma et. al.[1] and thermodynamic calculations using Thermo-Calc software, different alloy composition - Ti - (38-43)Al - (1-7,5)[Nb,Cr,Zr] - were identified as promising for this concept. Therefore, samples were produced by arc melting and analyzed with respect to their phase transition temperature, microstructure and phase constitution. The results were compared to measurements done with the commercial used TiAl alloy TNM (Ti - 43, 5Al - 4Nb - 1Mo - 0,1B). [1] Kainuma, R, Fujita, Y. Mitsui, H., Ohnuma, I. and Ishida, K. (2000) Intermetallics, 8}, language = {en} } @misc{Kathoefer, author = {Kath{\"o}fer, Fabian}, title = {Phase composition and microstructure of TiAl-Zr alloys}, series = {Intermetallics 2019, International Conference, 30 September-04 October 2019, Educational Center Kloster Banz, Germany}, journal = {Intermetallics 2019, International Conference, 30 September-04 October 2019, Educational Center Kloster Banz, Germany}, isbn = {978-3-948023-07-2}, pages = {1}, abstract = {Titanium aluminide alloys (TiAl), especially alloys based on the intermetallic γ-phase, have attracted much attention as a substitute for Ni-based alloys as highly promising high temperature structural materials. This is due to their low density, high specific strength and specific elastic moduli as well as good corrosion resistance [1,2]. However, the processing of these alloys is still challenging and expensive, since for example the necessary temperatures for hot forming between 1100 °C and 1250 °C bring currently available die materials to their limits. Fortunately, by an appropriate tuning of the alloy composition it is possible to form phases and microstructures at the forming temperature which provide good deformation capabilities. The addition of alloying elements can not only lead to a shift of the transition temperatures of the phases but can also improve mechanical properties. For instance the addition of Zirconium (Zr), a β-stabilizing element, lowers the phase transformation temperatures of the 'softer' disordered α and β phases and has other additional beneficial effects e.g. solution strengthening on TiAl alloys [3]. While TiAl systems with addition of elements like Niobium and Molybdenum are well investigated so far, only a few studies on the effects of Zr additions in TiAl systems exist. References [1] F. Appel, J. Paul, M. Oehring (Eds.), Gamma Titamium Aluminde Alloys - science and technology, Wiley-VCH, Weinheim, 2011. [2] F. Appel, H. Clemens, F.D. Fischer, Modeling concepts for intermetallic titanium aluminides, Progress in Materials Science 81 (2016) 55-124. [3] X.J. Jiang, Y.K. Zhou, Z.H. Feng, C.Q. Xia, C.L. Tan, S.X. Liang, X.Y. Zhang et al., Influence of Zr content on β-phase stability in α-type Ti-Al alloys, Materials Science and Engineering: A 639 (2015) 407-411.}, language = {en} }