What is the development history of magnets?

　　In early twentieth Century, people mainly use carbon steel, tungsten steel, chromium and cobalt as materials of permanent magnets. At the end of nineteen thirties, the successful development of AlNiCo magnets' materials makes permanent magnetic material for large-scale applications possible.

　　In fifty, barium ferrite permanent magnet's appearance not only reduces the cost, but the permanent magnetic material broadens the scope of application of the high frequency field. To sixty time, rare earth cobalt permanent magnet has opened up a new era for the permanent magnet's application.

　　In 1967, Strnat and other people of the United States Dayton University, powder bonding method successfully made SmCo5 permanent magnets, which mark the arrival of the era of rare earth permanent magnet. So far, the rare earth permanent magnet has experienced the first generation of SmCo5, the second generation of precipitation hardening type Sm2Co17, to the development of the third generation of Nd-Fe-B permanent magnetic materials. In addition, in history, what is used as permanent magnetic materials has Cu-Ni-Fe, Fe-Co-Mo, Fe-Co-V, MnBi, A1MnC alloy.

　　Currently, Ba and Sr ferrite still use the largest amount of permanent magnetic material, but many of its applications are gradually being replaced by class Nd-Fe-B material. Also, the rare earth permanent magnetic materials' production has greatly exceeded the ferrite permanent magnetic materials, rare earth permanent magnetic materials' production has developed into a big industry.