Regensburg 2000 – wissenschaftliches Programm

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AM: Magnetismus

AM 2: Legierungen der Übergangsmetalle, intermetallische Phasen, unterkühlte Metallschmelzen

AM 2.2: Vortrag

Montag, 27. März 2000, 09:45–10:00, H22

Phase selection in undercooled Nd-Fe-B alloys with Ti and C addition — •Octavian Filip¹, Regina Hermann², Wolfgang Gruner², and Ludwig Schultz² — ¹IFW Dresden, Helmholtzstrasse 20, 01069 Dresden — ²IFW Dresden

The microstructure and the solidification kinetics of stoichiometric Nd-Fe-B alloys with Ti and C addition has been investigated using the electromagnetic levitation technique. Melt drops with different amounts of Ti_x and C_x addition (x=0.5-3 at %) were undercooled and quenched at distinct undercooling levels onto chill substrates. During slow undercooling the properitectic γ-Fe phase solidifies primarily whereas fast undercooling during quenching favors the primary growth of the 2-14-1 phase. Ti and C form the stable TiC phase which leads to fine distributed Fe-dendrites and to grain refinement. The growth velocity of the 2-14-1 phase is reduced to about 0.5mm/s compared to the alloy without additions. Ti is slightly soluble (<1 at%) in the 2-14-1 phase. The different types of chemical binding of carbon were investigated with chemical methods in order to distinguish between bounded and free carbon content.