Exploration of the magnetic field effect on the orientation of Nd2Fe14B crystallites at high temperatures

An experimental study of the temperature dependent variation in orientation, induced by a high magnetic field, of Nd2Fe14B single crystal grains in a NdCu liquid eutectic has been carried out. Nd2Fe14B anisotropy in the paramagnetic state is shown to persist along the c-axis direction and to be large enough to allow orientation of Nd2Fe14B single-crystal grains with the c-axis parallel to the applied field direction for temperatures up to 1100 C. At higher temperatures, a misorientation process is observed to occur during the formation of Nd2Fe14B grains in a high magnetic field. This results from a decrease in the size of the solid nuclei remaining in the liquid melt above 1100 C. Consequently, the magnetic anisotropy energy associated with these nuclei is not sufficient to induce orientation or to orient crystal growth in the c-direction, in a high magnetic field. (orig.)