OVERVIEW OF CIENTIFIC AND TECNOLOGY THUST-A EUROPEAN PERSPECTIVE AND STABILITY OF NdFeB PERMANENT MAGNETS

The influence of interstitial hydrogen on the magnetic properties of the Nd2Fe14B-type phases (where R is a particular rare earth metal) was studied extensively during the CEAM program me. Hydrogen additions increased the Curie temperature and iron magnetization. The absorption process also results in the decrepitation of the bulk materials and this was exploited in the production of sintered magnets (see later). Unfonunately the anisotropy field of Nd2Fe14B at room temperature is substantially reduced so that it does not appear possible to make permanent magnets from the hydride material and it is necessary to remove the interstitial hydrogen in order to restore coercivity.