Dresden 2003 – wissenschaftliches Programm
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MA: Magnetismus
MA 3: Magnetische Materialien
MA 3.11: Vortrag
Montag, 24. März 2003, 12:45–13:00, HSZ/401
Magnetic Properties of Undercooled Co and Co-Au Alloy Melts — •Sven Reutzel1,2 and Dieter M. Herlach1 — 1Institute of Experimental Physics, Ruhr-University of Bochum, Germany — 2Institute of Space Simulation, German Aerospace Center Cologne, Germany
Co-based melts in a glass flux can be undercooled nearly as strong as samples processed containerlessly by electromagnetic levitation. The undercooling technique is combined with the use of a Faraday-balance to measure magnetic susceptibility on highly undercooled melts [1]. The magnetic susceptibility of Co and Co100−xAux alloys ( x = 10, 15, 20) is investigated as a function of temperature from stable liquid to undercooled liquid state. The results show that the magnetic susceptibility of the liquid undercooled samples follows a Curie-Weiss behavior, from which Curie temperature and magnetic moments are inferred. In no case an undercooling below the Curie-temperature was achieved. Differential thermal analyses on deeply undercooled Co-Au alloys by Wilde reveal a distinct increase of undercooling with decreasing Co-concentration [2]. Our measurements show that the nucleation temperatures measured by Wilde coincide with Curie temperature of liquid state. Magnetic contributions to crystal nucleation are assumed and will be discussed.
[1] S. Reutzel, D.M. Herlach, Adv. Eng. Mat., vol. 3 (2001) No. 1-2, 65-67
[2] G.Wilde, Ph.D.-thesis, Technical University Berlin, 1997
This work is financially supported by the Deutsche Forschungsgemeinschaft DFG.