Effects of Ho nanopowders intergranular addition on microstructure and properties of sintered Nd–Fe–B

Abstract

Nd–Fe–B magnetic materials were prepared using the binary alloy method with addition of Ho nanopowder to grain boundaries to improve the magnetic, mechanical properties, and corrosion-resistant performance. The morphology, phase, magnetic, mechanical properties, and corrosion-resistant performance of (PrNd)_29.9Dy_0.1B₁Co_0.1Cu_0.15Fe_bal-xHo_x (x denote mass fraction is 0.0 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, and 0.8 wt%, respectively) were analyzed. The results indicate that the coercive forces were enhanced with the increase of Ho content, but the remanence and maximum magnetic energy product decreased slowly in the Ho content range of 0–0.6%, and decreased rapidly in the Ho content range of 0.6–0.8%. When adding 0.6% Ho powders, the combination property of samples was the best; the coercive force reached 13.34 kOe, increased by 1.3%, and the remanence and maximum magnetic energy product decreased by only 0.3% and 0.2%, respectively. In the 3.5%NaCl solution, the sample with the addition of 0.6% Ho powders had the smallest corrosion current, reaching 3.273 × 10⁻⁷A/cm², which was down to 1/10, and the orientation degree of samples was 1.56, determined by calculating the I₍₀₀₆₎/I₍₁₀₅₎, the magnet density increased by 1.6%, reaching 7.52 g/cm³, with magnet hardness reaching 599.58 HV, up 8.2%.