Berlin 2005 – scientific programme

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.150: Poster

Monday, March 7, 2005, 14:00–18:00, Poster TU C

Corrosion of Nd-Fe-B magnets in aqueous environments — •Mihaela Rada, Annett Gebert, Oliver Gutfleisch, and Ludwig Schultz — IFW Dresden, Postfach 27 0116, 01171

The corrosion properties of hot compacted Nd₂Fe₁₄B/Fe (0 to 35 wt. %) nanocomposites (exhibiting remanence enhancement) produced from intensively milled powders and of polymer-bonded nanocrystalline magnets made from commercial rapidly quenched NdFeB-based powders with compositions varying from the Nd-rich to slightly Fe-rich range are evaluated in neutral and acidic aqueous media. The electrochemical properties of the magnets are discussed with respect to the behaviour of their single phases (Nd-rich phase, Fe, Fe₃B and Nd₂Fe₁₄B). Polymer-bonded magnets of different compositions have a significantly improved environmental resistance as compared to hot pressed magnets. Slight enrichment in Fe content and additions like Co and Nb improve their corrosion behaviour. For nanocomposites with increasing Fe content up to 35 wt. % decreasing corrosion rates as well as increasing passivation ability is detected. Effects of grain orientation on the corrosion rate are studied in detail for textured sintered magnets.