Effects of the conventional HDDR process and the additions of Co and Zr on anisotropy of HDDR Pr–Fe–B-type magnetic materials

Abstract Effects of the conventional hydrogenation disproportionation desorption recombination (HDDR) process and the additions of Co and Zr on anisotropy of HDDR PrFeB-type magnetic materials are investigated. The results show that the degree of anisotropy in conventional HDDR Pr13Fe80B7 materials decreases monotonically with the prolonged disproportionation time, and short disproportionation time is helpful for preparing highly anisotropic Pr13Fe80B7 material. However, it is notable that the degree of anisotropy in conventional HDDR Pr13Fe80B7 materials is significantly smaller than that in solid-HDDR Pr13Fe80B7 materials with the same disproportionation time. At the same time, it is found that the addition of Co and Zr may make HDDR Pr–Fe–B materials that have higher anisotropy compared with HDDR pure ternary Pr13Fe80B7 materials under the same HDDR process, but their degree of anisotropy will also decrease monotonically with the prolonged disproportionation time, and will be close to zero when the disproportionation time is greater than 20 h. Based on this, the origin of anisotropy is discussed by X-ray diffraction (XRD) investigations for the disproportionated products of the above alloys. The results show that the origin of anisotropy in HDDR Pr–Fe–B materials with the addition of Co or Zr may differ from that in HDDR pure Pr13Fe80B7 materials, and the former maybe from the residual “Pr2(Fe,Co,Zr)14B” nucleus while the latter is not. Finally, it is also found that HDDR Pr–Fe–B materials with Co or Zr can obtain high-magnetic properties even if the high-desorption temperature is used, and this shows the addition of Co and Zr may make HDDR Pr–Fe–B materials that have a larger process temperature range.