Page 11 - Дисертація_Борух

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shown that the alloy powder particles are sintered. The material is nanostructured

with grain sizes of the main ferromagnetic phase of 60-90 nm. On the example of

the SmCo 4,8V 0,2 alloy, grounded with ν = 200 rpm and τ = 6 h, it is shown that in

hydrogen the powder particles are sintered, a microstructure is formed with grain

sizes equal to ≈90-102 nm and a porosity <0.8%.

A method of heat treatment in hydrogen by HDDR of sintered SmCo 5 alloy

magnets for crushing their microstructure and improving magnetic properties is

proposed. After HD, traces of the SmCo 5 phase are detected. It is shown that after

HDDR the SmCo 5 phase dominates in the alloy; there are traces of samarium

oxide. The effect of recombination conditions at 850°C, 850°C with τ = 1 hour and

950°C on the microstructure and magnetic properties of magnets is investigated.

SEM and elemental analysis show that the magnets after recombination contain

two phases: SmCo 5 and Sm 2Co 7. As the temperature increases, the amount of

Sm 2Co 7 phase decreases. The SmCo 5 phase is highly dispersed, with grain sizes of

70-100 nm, after recombination at 850°C with grains coarsening to 90-170 nm,

after recombination at 950°C. It is shown that after heat shielding by HDDR the

coercive force of the magnet reaches 49.0-49.7 kE. It is found that the residual

magnetization and specific magnetic energy increase with increasing temperature

and duration of recombination.

Keywords: neodymium-iron-boron alloys; samarium-cobalt alloys; HDDR

method; hydrogen treatment; nanostructure; magnetic anisotropy; texture;

sintering; porosity; phase transformations; diffusion; X-ray phase analysis;

coercive force.