Editors: | F. Kongoli, M. Calin, J.M. Dubois, K. Zuzek-Rozman |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2019 |
Pages: | 156 pages |
ISBN: | 978-1-989820-02-5 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Metal-bonded magnets based on YCo5-type nanocrystals [i] were produced by hot-compaction using a spark plasma-sintering device. Zn and Zn/Al metallic binders with a melting temperature of ̴ 420°C were employed to fabricate dense cylindrical magnets. Two different pressures were used for compaction. The pressure of 400 MPa provided a metal-bonded magnet with Vickers hardness (HV10) of 460 ± 20 Vickers. The temperature coefficients for remanence (α) and coercivity (β) were derived from magnetization vs. magnetic field measurements in the temperature range of 20°C – 150°C. Temperature coefficients α and β for the Zn/Al-bonded magnet pressed with 400 MPa were -0.055 %/°C and -0.201 %/°C, respectively. The field emission gun scanning electron microscope revealed a ‘core-shell’-type microstructure. The pure YCo4.8Fe0.2 phase was detected in the core region whereas the shell was enriched with non-ferromagnetic Zn or Zn/Al phases. The high-resolution transmission electron microscope revealed the presence of clusters with ̴ 20 nm YCo4.8Fe0.2 grains. In the Zn/Al-bonded magnet, fabricated at 400 MPa, the coercivity µ0Hci, remanent magnetization σ and energy product (BH)max were 0.87 T, 39.3 Am2/kg and 23.4 kJ/m3, respectively.[ii]