Abstract
The 30 m and 100 m long drop tubes at the Marshall Space Flight Center have been used to obtain large undercooling in Nb-Ge alloys. Electron beam melting has been used to obtain drops approximately 2.5 mm in diameter. In the 30 m tube many specimens fell the length of the tube without solidifying, and were ultimately liquid quenched in oil. The amount of undercooling prior to the quench was usually around 0.13T;m. In the 100 m tube, freezing generally initiated during free fall, and the maximum undercooling was around 0.22Tm. Microstructures were characterized by a combination of X-ray diffraction, optical microscopy, and scanning electron microscopy with energy dispersive analysis by X-rays. A variety of interesting microstructures was observed.
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Evans, N.D., Hofmeister, W.H., Bayuzick, R.J. et al. Solidification of Nb-Ge alloys in long drop tubes. Metall Trans A 17, 973–981 (1986). https://doi.org/10.1007/BF02661263
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DOI: https://doi.org/10.1007/BF02661263