Crystallization of Nd₂Fe₁₇B_x from stoichiometric melt composition

Containerless solidification of gas-atomized Nd₁₀Fe₈₅B₅ melt droplets was carried out using the drop tube technique. The phase constituents and microstructure of the solidified samples were investigated by means of powder X-ray diffraction analysis, thermomagnetic analysis, and scanning electron microscopy. Besides α-Fe and Nd₂Fe₁₄B, non-equilibrium phases such as Nd₂Fe₁₇B_x, ε-Nd, and Nd_1.1Fe₄B₄ were identified. The microstructure of the samples was categorized into three types, including a quasi-single phase one that consists mainly of Nd₂Fe₁₇B_x dendrites. The lattice parameters and Curie temperature of Nd₂Fe₁₇B_x were determined, and compared with those of the same type phase crystallized in Nd-rich Nd-Fe-B melt compositions. The results were discussed with respect to the stoichiometry, formation as well as potential application of Nd₂Fe₁₇B_x.