Coercivity of nanocrystalline Nd-Fe-Co-Al-B alloys with low rare-earth content

The controlled nanocrystallization of Nd-Fe-Co-Al-B bulk amorphous tunes the coercivity, which is enhanced to 23 kOe, with a Curie temperature of 692 K. Ferromagnetic Nd2(Fe,Co,Al)14B nanocrystallites isolated by amorphous clusters coexist with antiferromagnetic Nd6(Fe,Co,Al)14. These magnetic properties are examined by the combination of X-ray diffraction, high-resolution transmission electron microscopy, magnetization measurements, and Mossbauer spectrometry. The grain size for optimal magnetic properties is around 40 nm.