报告题目: Research with Neutrons and Synchrotron Radiation on Advanced Titanium Aluminides

报 告 人: Prof. Svea Mayer

          Department of Materials Science, Montanuniversitt Leoben, Austria

时间: 5月8日（周三）上午9:00-10:30

地点: 师昌绪楼408房间

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摘要：

Intermetallic γ-TiAl based alloys are considered as key structural materials in advanced jet engines. From its very beginning the development of these alloys, which consist of phases with ordered crystal lattice, was accompanied by the application of diffraction and scattering techniques. In particular, high-energy X-ray diffraction, neutron diffraction and small-angle scattering techniques, such as small-angle X-ray scattering and small-angle neutron scattering, have found their way into a broad range of applications, comprising both fundamental as well as processing- and application-related aspects. Among the various techniques available, high-energy X-ray diffraction experiments represent a particularly powerful and versatile tool of investigation for the detailed characterization of phases. In this way, the evolution of phase fractions as function of temperature, time or specific deformation parameters can be studied. The phase fractions gained during such a slow in situ experiment, confirmed and extended by results gained in an ex situ experiment or theoretically by thermodynamic calculations, allow the establishment of phase fraction diagrams. Such detailed studies on the phase transformation behavior of γ-TiAl based alloys play a key role in the alloy development, as by their use chemical compositions can be optimized, the influence of additional alloying elements studied, the accuracy of predicted phase diagrams verified and thermodynamic databases modified. Regarding the study of precipitation processes, small-angle scattering techniques proved to be a useful tool. In TiAl alloys containing small amounts of C, for example, small-angle X-ray scattering measurements were conducted to elucidate the formation of ultra-fine hierarchical structures by precipitation of p-type carbides within γ-laths. In case of coarse-grained materials, such as cast TiAl alloys, certain grain statistics due to an enlargement of the probed volume is required. In this regard, neutron diffraction offers clear advantages. Furthermore, neutrons are well-suited for the investigation of ordering reactions in γ-TiAl based alloys.

报告人简介：

Prof. Svea Mayer received her PhD in 2009. Since then, she is leading the working group on phase transformations and high-temperature materials at the Department of Materials Science, Montanuniversitt Leoben. In 2011 she was accepted as assistant professor, started lecturing and was promoted to associate professor in 2018. One of her prime research topic is the use of neutrons and synchrotron radiation for the development of novel high-temperature materials. She is member of review panels and for her academic achievements she was awarded for example with the Georg-Sachs-Prize of the Deutsche Gesellschaft für Materialkunde e.V.