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The magnetic domain structure and related magnetic properties of (NdPr)_(16)Fe_(76)B_8 permanentmagnet have been studied by colloid-SEM method.In thermally demagnetized state,the ma-trix grains in the magnet generally exhibit multidomain structure,i.e.,180° plate-like indi-vidual domain and a few spike-like or maze-like domains.The average width of the domainmeasured was 1.5μm.Grain size of single-domain was observed to be generally about 1μmand only a few up to 3μm.The results calculated are:the domain wall energy γ=36MJ/m~2,the exchange constant A=4.5×10~(-11)J/m,the domain wall width δ=15.7nm,and the critical grain diameter of single-domain D_c=0.5μm.The dependence of high magnet-ic field gradient at grain boundaries in different magnetization directions in the adjacent mag-netic domains located on both sides of grain boundaries and the effect of microstructure on thevalues of K,A and δ were discussed.
The magnetic domain structure and related magnetic properties of (NdPr) _ (16) Fe_ (76) B_8 permanentmagnet have been studied by colloid-SEM method. Thermally demagnetized state, the ma-trix grains in the magnet generally exhibit multidomain structure, ie , 180 ° plate-like indi-vidual domain and a few spike-like or maze-like domains. The average width of the domain has been 1.5 μm. Grain size of single-domain was observed to be generally about 1 μmand only a few up to 3μm. The results calculated are: the domain wall energy γ = 36MJ / m ~ 2, the exchange constant A = 4.5 × 10 ~ (-11) J / m, the domain wall width δ = 15.7nm, and the critical grain diameter of single-domain D_c = 0.5 μm. dependence of high magnet-ic field gradient at grain boundaries in different magnetization directions in the adjacent mag-netic domains located on both sides of grain boundaries and the effect of microstructure on the values of K, A and δ were discussed.