Hamburg 2001 – wissenschaftliches Programm
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AM: Magnetismus
AM 8: Dauermagnetische Werkstoffe und Legierungen
AM 8.4: Vortrag
Dienstag, 27. März 2001, 12:15–12:30, S 5.4
Metastable borides and the inducement of texture in Pr2Fe14B-type magnets produced by HDDR — •O. Gutfleisch1, A. Teresiak1, B. Gebel1, K.-H. Müller1, N.B. Cannesan2, D. Brown2, and I.R. Harris2 — 1IFW Dresden, Institute of Metallic Materials, POB 270016, 01171 Dresden — 2School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, UK
The hydrogenation-disproportionation-desorption-recombination (HDDR) process is well established as a method for the production of highly coercive Nd2Fe14B magnets. Here, a modified HDDR process has been applied to Pr2(Fe,Co,Zr)14B-type alloys. XRD and Rietveld analysis show that a Fe3B phase observed in a Pr13.7Fe80.3B6 alloy solid-disproportionated at 875o is transformed to Fe2B and bcc Fe on further hydrogen annealing and that the formation of Fe3B is partly suppressed when the alloy is processed at 800o. No residual 2-14-1-type phases are observed after disproportionation of Pr13.7Fe63.5Co16.7Zr0.1B6 alloy but here a new intermediate boride phase, Pr(Fe,Co)12B6 (rhombohedral R3m), is found. Pr(Fe,Co)12B6 transforms to (Fe,Co)2B and α-(Fe,Co) on further hydrogen annealing or conventional disproportionation. For both alloys it is found that processing at higher temperature leads to a better texture on recombination. The role of the Co and Zr additives is not primarily the stabilization of the 2-14-1 matrix phase against hydrogen disproportionation but more importantly the stabilization of intermediate boride phases.