Dependence of coercivity on the intergranular phase for nanocrystalline Nd-Fe-B magnet

Assume that the intergranular phase (IP) existing between adjacent grains is a weak magnetic phase, and could weaken or interrupt the intergrain exchange-coupling interaction (IECI). Using our proposed cubic-grain anisotropy model, we investigate the effects of IP's thickness d, and its anisotropy constant K1(0) on the coercivity of nanocrystalline Nd-Fe-B magnet. Calculation results indicate that the coercivity increases with increasing d, but decreases with increasing K1(0). When d = 1.2 nm and K1(0) = 0.5K1 (K1 is the common anisotropy constant of the bulk Nd-Fe-B material), our calculated results are consistent with available experimental data.