Preparation of Nd2Fe14B Single Domain Particles from Nd-Fe-B Alloy Ingot Using a Combination of HDDR and Mechanical Milling

Abstract

This study examined the feasibility of the combining HDDR-process (hydrogenation, disproportionation, desorption and recombination) with mechanical milling to prepare single domain Nd₂Fe 14 B particles from a Nd-Fe-B alloy ingot. The Nd 15 Fe 77 B? alloy was HDDR-treated and then subjected to a roller-milling. In the HDDRtreated Nd 15 Fe 77 B? alloy, very small Nd₂Fe 14 B grains comparable to their critical single domain size (0.3 ㎛) were observed. These fine individual grains were separated successfully along the grain boundaries by a rollermilling. The separated Nd₂Fe 14 B grains were found to be single domain particles. These results suggest that single domain particles of the Nd₂Fe 14 B phase can be prepared from a Nd-Fe-B ingot alloy by combining a HDDR-process with mechanical milling.