Influences of Original Alloy Microstructure on Magnetic Properties of Isotropic HDDR-Treated Nd-Fe-B Powder

We investigated influences of original alloy microstructure on magnetic properties of the isotropic HDDR (hydrogenation-decomposition-desorption-recombination)-treated Nd sub 12.6 Fe sub 79.0 Co sub 2.4 B sub 6.0 powder by comparing two types of starting materials, i.e., the strip cast (SC) alloy and the conventional book-mold cast (BMC) alloy. It was found that utilizing the SC alloy can achieve better I-H loop squareness, and consequently higher remanence in the final powder. The powder prepared from the SC alloy exhibits a more uniform grain structure of the recombined Nd sub 2 Fe sub 14 B phase, which is thought to be closely related to its good loop squareness. The effect of using the SC alloy is supposed to be attributed to the complete elimination of alpha -Fe particles before the HDDR treatment.