The role of heavy rare earth metal Tb instead of Nd

Adding Tb to the sintered NdFeB magnet to partially replace Nd has the same effect as the replacement of Nd by Dy, but the anisotropic field HA of Tb 2Fe14B is higher, so it can more effectively improve the coercive force of the permanent magnet. But Tb has less reserves in rare earth mines than Dy, and the price is higher.