The Materials Science Laboratory - Electromagnetic Levitator (EML) on the International Space Station: Thermophysical properties of a TiAl alloy (GE 48-2-2) in the liquid phase
- Paper number
IAC-18,A2,6,13,x46100
- Author
Dr. Rainer Wunderlich, Germany, Ulm University
- Coauthor
Dr. Markus Mohr, Germany, Ulm University
- Coauthor
Dr. Ulrike HECHT, Germany, Access e.V.
- Coauthor
Prof. Douglas MATSON, United States
- Coauthor
Mr. Michael BRIENZA, United States
- Coauthor
Mr. Alex KLEIN, United States
- Coauthor
Prof. Robert HYERS, United States, University of Massachusetts
- Coauthor
Prof.Dr. Hans Fecht, Germany, Ulm University
- Year
2018
- Abstract
In this contribution we describe thermophysical property measurements with the containerless electromagnetic processing device MSL-EML on board the International Space Station ISS. The alloy GE 48-2-2 (Ti48-Al48-2Nb-2Cr) provides a good example of the use of the MSL-EML on ISS. First, the alloy has a high liquidus temperature of 1510 °C. Second, Ti-Al alloys are very reactive in the liquid phase. Both properties make processing in conventional thermoanalytic equipment difficult and fraught with error. GE 48-2-2 is an industrial alloy, thermophysical properties are required for modelling of casting and solidification. Moreover, the nucleation kinetics such as the growth velocity and the sequence of metastable and stable phase formation and its possible control by electromagnetic stirring are of interest from an applied point of view, as these mechanisms affect the final microstructure or make necessary elaborate high temperature annealing to obtain the final structural material. But also from a more basic materials science point of view including an investigation of thermophysical properties in the undercooled liquid phase is of interest.\\ The whole thermophysical property measurement capabilities of the MSL-EML on ISS could successfully be applied to the $\gamma$-TiAl alloy providing a set of thermophysical property data and characteristics in an way unprecedented from any device. These were: measurement of the density and electrical resistivity in the liquid phase, surface tension and viscosity by the oscillating drop method, non-contact calorimetry based on electromagnetic induction in the stable and undercooled liquid phase, measurement of the solidification growth velocity and the effect of magnetic stirring on nucleation kinetics and undercooling. An overview of the technical realizations of the different thermoanalytic and kinetic investigations will be presented and selected results of the surface tension and viscosity as a function of temperature will be discussed.\\ The work presented was supported by the German Space Agency DLR, contract number 50WM0041, the European Space agency ESA in the framework of its MAP programme, AO-99-022 (14306/01/NL/SH), and by the National Aerospace and Space Adminstration of the United States, NASA. (add contract numbers if you wish/need)
- Abstract document
- Manuscript document
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