Enhanced coercivity in SmCo5 magnet subjected to hydrogen treatment

Highlights: • Coercivity of the SmCo₅ magnets, μ₀H_c≤ 4.97 T. • Impact of HDDR on the properties. • Nanostructure of the sintered magnets. -- Abstract: The relations between the phase recombination conditions and phase content, microstructure, and magnetic properties of sintered SmCo₅-based permanent magnets, subjected to hydrogen treatment, were studied by X-ray diffraction, scanning electron microscopy, and magnetic hysteresis loop measurements. Recombination of the disproportionation products, SmH_2±x, Co, and remains of SmCo₅ phase, was carried out by heating the alloy in a vacuum to 850 °C with and without holding it for 1 h, and by heating it to 950 °. It was shown that after recombination, the coercivity of the magnet, μ₀H_c, reached the value of 4.90–4.97 T. The remnant magnetization increased from 27.7 to 43.5, and to 46.7 Am²/kg with increasing holding time during recombination from 0 to 1 h at a temperature of 850 °, and with increased recombination temperature to 950 °C. The hysteresis loop rectangularity changed from 77 to 74.6, and to 78.8% under the same conditions.