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

This study examined the feasibility of the combining HDDR-process (hydrogenation, disproportionation, desorption and recombination) with mechanical milling to prepare single domain $Nd_2Fe₁₄B$ particles from a Nd-Fe-B alloy ingot. The $Nd₁₅Fe₇₇B_8$ alloy was HDDR-treated and then subjected to a roller-milling. In the HDDR-treated $Nd₁₅Fe₇₇B_8$ alloy, very small $Nd_2Fe₁₄B$ grains comparable to their critical single domain size(0.3 ${\mu}m$) were observed. These fine individual grains were separated successfully along the grain boundaries by a roller-milling. The separated $Nd_2Fe₁₄B$ grains were found to be single domain particles. These results suggest that single domain particles of the $Nd_2Fe₁₄B$ phase can be prepared from a Nd-Fe-B ingot alloy by combining a HDDR-process with mechanical milling.