Münster 1999 – scientific programme

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M: Metallphysik

M 2: Struktur und Umwandlungen I

M 2.9: Talk

Monday, March 22, 1999, 12:45–13:00, S 8

Phase evolution in directly solidified and directly quenched Nd-Fe-B alloys with different additions (TiC, Mo, Al) — •Regina Hermann , Octavian Filip, Ingrid Bächer, and Ludwig Schultz — IFW Dresden, PF 270016, 01171 Dresden

Microstructures of near-stoichiometric Nd-Fe-B alloys with the additions TiC(6at%), Mo(6at%)and Al(2at%) have been investigated. The samples were both directly solidified and directly quenched onto a copper substrate. After direct solidification the samples were additionally annealed at 1050^∘ C for 5 and 10 hours, respectively. It has been found that small deviations of the Al content and the heat treatment conditions influence the volume fraction of the intergranular δ phase strongly and with that the wettability of the hard magnetic 2-14-1 (Φ) phase. Directly quenched TiC doped samples show in comparison to directly solidified and non-doped material a tremendous grain refinement. The growth of large Fe dendrites is prevented. TiC is scarcely soluble in the 2-14-1 phase. It is assumed that TiC decreases drastically the growth velocity of the 2-14-1 phase. Mo doped samples show similar fine microstructure. A non-negligible solubility of Mo in all phas! es was observed. It is believed that boride-rich phases surround the 2-14-1 grains and inhibit the grain growth.