New method of chemical synthesis for nanostructured Nd-Fe-B alloy

Abstract

A new method of chemical synthesis has been developed for the nanostructured Nd-Fe-B alloy using nanoparticles of Nd2O3, Fe2O3, and Fe3BO6 powders. The nanoparticles of Nd2O3, Fe2O3, and Fe3BO6 were obtained through chemical precipitation followed by calcination. The Nd2O3 nanoparticles have a rod-like shape with a diameter of 28 nm and a length of 118 nm. The α-Fe2O3 nanoparticles have an ellipsoidal shape with an average diameter of 55 ± 11 nm. Additionally, a powder mixture of nanoparticles containing 74.4 wt% α-Fe2O3 and 25.6 wt% Fe3BO6 was obtained, and the particles exhibit an irregular shape with an average diameter of 50 ± 10 nm. A mechanism for the formation of the nanostructured Nd-Fe-B alloy from the Nd2O3, Fe2O3, and Fe3BO6 nanoparticles was proposed. It was found that during the initial stage of the reductive-diffusion process, nanopowders of NdFeO3, NdBO3, and α-Fe2O3 are formed. In the second stage of the reductive-diffusion process, nanopowders consisting of phases of 36.7 wt% Nd2Fe14B, 10.9 wt% α-Fe, and 52.4 wt% CaO are formed. After removing CaO, the obtained nanostructured Nd-Fe-B alloy consists of 76.1 wt% Nd2Fe14B, a hard magnetic phase, and 23.9 wt% α-Fe, a soft magnetic phase. The average particle size of the nanostructured Nd-Fe-B alloy is 110 ± 35 nm. The nanostructured Nd-Fe-B alloy powders exhibit the following magnetic characteristics: coercive force (Hc) of 3295 Oe, saturation magnetization (Ms) of 132.01 A·m2/kg, and residual magnetization (Mr) of 99.53 A·m2/kg.