Magnetic Properties of Anisotropic Didymium-Fe-Co-Nb-V-Y-B Magnets by using Hot-Forming Process

Abstract

The experiment was aiming for making anisotropic magnet by using hot-forming process. And this experiment was carried out to investigate the effects of Cu addition, and hot-forming temperature on magnetic properties of Didymium-Fe-Co-Nb-Y-B and Didymium-Fe-Co-Nb-V-Y-B alloys. The results are summarized as follows:1) In the X-ray diffraction patterns which were taken in the direction of applied compressive stress in the hot-forming process, large peaks corresponding to (004), (105) and (006) planes were observed. These planes are facing the direction of the c-axis of the Nd₂Fe₁₄B-type crystal. These observations suggest that crystallites are oriented toward the c-axis by the hot-forming process.2) The optimized preparatory conditions for the anisotropic magnet Di_12.5Fe_68.3Co₁₀Nb₁V₁Y_0.7Cu_0.5B₆ are as follows: roller velocity in the process of preparing the melt-spun ribbons : 25 m/s, and temperature of the hot-forming process: 840°C. Typical magnetic properties of the anisotropic magnets obtained: J_r=1.041T, H_cJ=812.5 kA/m, H_cB=561.7 kA/m, (BH)_max=176.8 kJ/m³, (J_r - J_r')/J_r × 100 =54.5 %. The α-Fe type phase is contained several percent in the sample. Good results are obtained in this study, which can be related to the industrial “die-upset process”.