Regensburg 2004 – scientific programme

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M: Metallphysik

M 8: Phasenumwandlungen I

M 8.5: Talk

Monday, March 8, 2004, 15:45–16:00, H4

Characterization of hard magnetic phase in mould-cast and directionally solidified Nd-Fe alloys — •G. Kumar¹, R. Sato², J. Eckert³, W. Löser¹, L. Schultz¹, and R. Grössinger² — ¹IFW Dresden, Institute for Metallic Materials, D-01171 Dresden, Germany — ²Institut für Experimentalphysik, TU Wien, A-1040 Vienna, Austria. — ³TU Darmstadt, FB 11 Materials- und Geowissenschaften, FG Physikalische Metallkunde, D-64287 Darmstadt, Germany.

In this work, Nd₈₀Fe₂₀ alloys were prepared by copper mould casting and directional solidification (DS) to obtain a coarse microstructure. The mould-cast samples exhibit a fine globular eutectic structure and show high room temperature coercivity (  5 kOe). The DS samples exhibit large grains (composition close to NdFe₂) in peritectic morphology but show no coercivity. The NdFe₂ grains (formed in the DS samples) show clear magnetic domains with uniaxial anisotropy indicating that NdFe2 is not a cubic phase. HRTEM equipped with selected area diffraction (SAD) was used to identify the crystal structure of NdFe₂-type phase observed in the DS samples. AC susceptibility and Mössbauer studies were used to identify different magnetic phases. Acknowledgement The work was supported by the German Science Foundation (DFG) via the DFG priority program "Phasenumwandlungen in mehrkomponentigen Schmelzen" under grant Ec 111/11-1,2.