Magnetic materials have a long history, which can be traced back to the compass invented in the warring states period of China. According to the properties of magnetic materials, they can be summarized as hard magnetic materials (or permanent magnetic materials), soft magnetic materials and magneto-optical materials. Among them, permanent magnet materials are particularly attractive.
Permanent magnet material is the material after magnetization, no longer need to generate magnetic field from external power supply, it is also called permanent magnet. Permanent magnetic materials can be divided into three categories: one is aluminum nickel diamond permanent magnetic materials; Second, ferrite permanent magnet; Third, rare earth permanent magnet materials. Rare earth permanent magnet material occupies a particularly important position in the kingdom of permanent magnet materials, and its development speed is amazing. The first generation of rare earth permanent magnet such as samarium cobalt alloy was developed in the 1960s, and the second generation of rare earth permanent magnet was developed in the 1970s. In the 1980s, the development and application of ndfeb can be called the third generation of rare earth permanent magnet. It can be seen that on average, a generation of rare earth permanent magnet was developed in 10 years.
The birth of ndfeb is regarded as a great leap forward in the development history of permanent magnet materials. Its low price, superior magnetic properties, low density, maximum magnetic energy accumulation (400KJ/m3). Recently, the application range of ndfeb can be extended by adding other groups, such as CO, NI, MO, etc., which can improve corrosion resistance, temperature stability and coercivity. Ndfeb permanent magnet material is mainly used for motor manufacturing in industry. Its outstanding performance advantages are small size, light weight, high power ratio and high efficiency. The other major contribution of ndfeb is as the core of the medical NMR imaging instrument. In addition, it can also be used as microphone, high frequency speaker and stereo earphone in electro-acoustic devices, as well as magnetic sulfur seal, magnetic water and so on.
China is the world's most abundant rare earth country, the successful development of high temperature and low temperature coefficient of the new ndfeb permanent magnet material, all kinds of performance better than foreign products, especially with a lower temperature coefficient, the cost is less than 5% of foreign markets, occupy a certain foreign market. Nowadays, China and abroad are developing the fourth generation of rare earth permanent magnet materials, that is, developing new generation of rare earth permanent magnet materials with better performance and more economical, such as rare earth ferronitrogen system and rare earth ferrotransition metal system (RFeM).
High performance metal materials rising in the century also include high-strength nuclear al-li alloy and ultra-fine particle metal materials, etc., which occupy an important position in the high-tech revolution and have a broad and growing application prospect.