NdFeB rare earth permanent magnet is known as the third generation

NdFeB rare earth permanent magnet is known as the third generation, it is by far the highest of the permanent magnetic materials. Sintered NdFeB alloy main phase is an intermetallic compound Nd2Fe14B, its saturation magnetic polarization (Js) of 1.6T [1]. Since the sintered NdFeB permanent magnetic alloy is composed of Nd2Fe14B main phase and a grain boundary phase, but Nd2Fe14B grain orientation by the process conditions, the current highest remanence can reach 1.5T. Germany vacuum melting company (Vacuumschmelze GmbH) consume a maximum energy product (BH) max reach 57MGOe NdFeB magnets. Domestic manufacturers can consume NdFeB N50 grade magnets, the maximum energy product reach 53MGOe. The ratio of the main phase alloy progress, the degree of orientation and density of the magnet progress grains can improve the maximum energy product of the magnet; but will not go beyond the single crystal Nd2Fe14B theoretical maximum energy product 64MGOe [1].

NdFeB room temperature demagnetization curve approximates a straight line. Thus, when the permanent magnet motor design, often choose high grade NdFeB (ie, information (BH) max height) to achieve high flux density. When the motor is running, due to the presence of alternating demagnetizing field, and when the load suddenly changes, back magnetic field generated by a large current moment, asked to choose a sufficiently high coercivity NdFeB magnets.

In the alloy add dysprosium (terbium) and other elements of progress NdFeB intrinsic coercivity (jHc), but the magnetic remanence (Br) will be reduced. Thus, high-performance NdFeB magnets used in wind turbines integrated its coercivity and remanence.