Investigation on Hard Magnetic Properties of Nanocomposite Permanent Magnets with Precipitate-Typed Microstructure by Micromagnetic Finite-Element Methods

摘要

The demagnetization curves, were calculated using micromagnetic finite-element method for nanocomposite Pr_2Fe_(14)B/alpha-Fe permanent magnets with precipitate-typed microstructure. Due to intergrain exchange coupling, both remanence enhancement and a single magnetic phase behavior in demagnetization curve were found. For the samples with the hard phase as the precipitate and the soft one as the matrix, a coercivity mu_0H_c of 0.78 T, a remanence J_r of 1.18 T and a large energy product (BH)_(max) of 200 kJ centre dot m~(-3) are obtained for the sample with hard grain size being 23 nm. While, for the sample with he soft phase as the precipitate, mu_0H_c of 0.95 T, J_r of 1.24 T and (BH)_(max) of 240 kJ centre dot m~(-3) are obtained for the sample with soft grain size being 10 001. The calculating results were compared with the experimental Pr_8Fe_(87)B_5 ribbons. The dependence of remanence and coercivity on the microstructure was discussed extensively.