Hamburg 2001 – scientific programme

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AM: Magnetismus

AM 9: Poster: Magnetowid. (1-17), Dü. Schichten (18-34), Oberfl
ächenmag. (35,36), Mikr. Methoden (37-45), Mikromag. (46-58), Phasenüberg. (59-77), Spektroskop. (78-91), Nanokr.Mat.(92-96), Anisotrop. (97-101), Schmelzen(102-104),Sonst/postdeadl.(105-109)

AM 9.103: Poster

Tuesday, March 27, 2001, 14:45–19:00, Foyer S 3

ELECTROCHEMCIAL HYDROGENATION BEHAVIOUR OF NdFeB MAGNETS — •A.A. El-Moneim, O. Gutfleisch, and A. Gebert — IFW Dresden, P.O. Box 27 00 16, D-01171 Dresden

The electrochemical hydrogenation of the three single phases constituting NdFeB magnets and nanocrystalline hot pressed magnets in 1 M NaOH solution has been examined using dc electrochemical methods, thermal desorption analysis, SEM, AES and XRD. The materials were charged over a wide range of cathodic current (2 100 mA) followed by a constant anodic discharge current. A plot of potential versus time during discharge shows an arrest charactersitic of the materials which absorb hydrogen and represents the quantity of the oxidized hydride. The results indicate that all the examined materials absorb hydrogen from aqueous solution. Relevant to the hydrogenation behaviour of single phases, the absorbed hydrogen atoms diffuse interstitially through 2-14-1 matrix phase at the initial stages but its selective character is partially covered up by the intergranular hydrogenation of Nd-rich phase at the later stages of hydrogenation process. The impact of hydrogen up-take on the corrosion behavior of single phases as well as NdFeB-base magnets has also been studied.