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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


  • The support of DESY management, User Office and GKSS beamline staff is highly acknowledged. Research activities leading to the presented HEXRD results received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under grant agreement n°226716. A part of this study was conducted within the framework of the BMBF project O3X3530A, Germany, and the Styrian Materials Cluster, Austria.


Being a strong β stabilizer, Mo has gained importance as an alloying element for so-called β/γ-TiAl alloys. Intermetallic TiAl-based alloys which contain a significant volume fraction of the body-centered cubic β-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 βo-phase is determined.