Combination and characteristics of NdFeB permanent magnets

　　NdFeB permanent magnets are intermetallic compounds, consisting of rare earth element R and iron, boron. R is primarily neodymium or combinations with other rare earth elements, sometimes also using cobalt, aluminum, vanadium and other elements to replace part of iron.

　　NdFeB permanent magnets have strong magnetic anisotropy and high saturation magnetization, the representation of the magnet component is Nd15Fe77B8 ( atomic ratio). In the permanent magnetic material, sintered NdFeB magnets have the highest performance, commercial products' maximum energy product ( BH ) max=360kJ/m3, intrinsic coercivity iHc reached 800～ 1400kA/m. But the magnet Curie is at a lower temperature (314℃), thermal stability and corrosion resistance is poor, which restrict the use at higher temperature, and in most cases, it needs to use the protective coating.

　　The manufacturing process of NdFeB permanent magnets has powder metallurgy method and melt quenching. Due to the magnetic performance, Nd-Fe-B type magnet has obtained the widespread application, mainly used for electric motor, generator, an acoustic wave transducer, sensor, medical devices and magnetic machinery.