The main phase Nd2Fe14B is the only hard magnetic phase with uniaxial anisotropy in the Nd-Fe-B permanent magnet（super strong magnets）, and its volume fraction accounts for more than 90% of the phases in the magnet, hence the main phase. The crystal structure is shown in Fig. 3: lattice constant a = 0.882nm, c = 1.224nm, c axis is easy axis, each cell contains four molecules of 68 atoms. Nd2Fe14B phase intrinsic magnetic properties: Curie temperature Tc = 585K, room temperature anisotropy constant K1 = 4.2MJ / m3, K2 = 0.7MJ / m3, anisotropic field Ha = 7.3T, room temperature saturation magnetic polarization Js = 1.61T. The basic domain structure parameters of Nd2Fe14B are: domain wall density d = 30MJ / m2, domain wall thickness d = 5.2nm, single domain particle critical dimension Dc = 0.26μm.
If the alloy element is added to the composition of the magnet, the crystal structure of the main phase does not change, but its intrinsic magnetic properties are changed, and the purpose of adding the alloying element is to improve the intrinsic coercivity or other characteristics of the magnet. It is worth noting that the addition of any alloying element to the magnet reduces the saturation magnetic polarization of the main phase Nd2Fe14B.
Article from NdFeB Industry Network