The aim of this study is to examine the effect of Zr addition and quenching conditions on magnetic properties of Fe-Nd-B alloys. The cooling rate is varied by changing the wheel velocity of a single roller apparatus. Suppression of crystallization of soft magnetic phases (α-Fe and Fe3B) by adding Zr is confirmed by comparing the X-ray diffraction patterns of Fe85−xNd10ZrxB5 and Fe80−xNd10ZrxB10 alloys with and without Zr atoms. In the former alloys with x=0∼11, the amorphous formation ability is the highest at x=5 and 7. X-ray diffraction patterns and TEM observation show that hyperfine grains of 2-14-1 compounds, several nano-meters in diameter, are formed at a critical wheel velocity. It is confirmed by the measurements of Curie temperature and magnetic hyperfine field that considerable amount of Zr is present in the Nd2Fe14B phase. In a high boron alloy (Fe70Nd10Zr5B15), high coercive force of 1.2 MA/m is observed. The present work suggests the possibility of further improvement of the magnetic properties by the addition of Zr atoms.
