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Direct determination of metastable phase diagram by synchrotron radiation experiments on undercooled metallic melts

: Notthoff, C.; Feuerbacher, B.; Franz, H.; Herlach, D.M.; Holland-Moritz, D.


Physical review letters 86 (2001), Nr.6, S.1038-1041
ISSN: 0031-9007
ISSN: 1079-7114
Fraunhofer INT ()
liquid metal; crystallisation; phase diagram; undercooling; magnetic levitation; x-ray diffraction; synchrotron radiation; nickel alloy; vanadium alloy; nucleation; metastable state

The phase selection process during the crystallization of undercooled metallic melt is studied in situ by combining the electromagnetic levitation technique with energy dispersive x-ray diffraction of synchrotron radiation. The crystallization of metastable bcc phase in binary Ni-V alloys was identified. A metastable phase diagram of Ni-V alloy is constructed, which shows the primarily solidifying phase as a function of composition and undercooling. The analysis within nucleation theory emphasizes the important role of metal oxide as a heterogeneous nucleation site controlling the phase selection.