Permanent magnets are generally divided into three types: ferrite, Alnico and rare earth magnets.Ferrite magnets are ceramic materials with iron oxide as their main component.AlNiCo magnets are alloys composed of metal aluminum, nickel, cobalt, iron and other trace metal elements.As for rare earth magnets, they are strong permanent magnets composed of rare earth element alloys, among which are common rare earth-cobalt magnets, samarium cobalt magnets and neodymium iron boron magnets (also known as neodymium magnets).Generally, ferromagnetic substances will have a hysteresis loop, and the shape and size of the hysteresis curve represent the advantages and disadvantages of the magnet material. Generally, there are two types of hysteresis curves, as shown in Figure 1. The BH curve and the 4πM-H curve are shown.Several important indicators include the residual magnetic flux density Br in the BH curve, the coercive force Hc or bHc, the magnetic energy product (BH) max, and the maximum induced magnetization 4πMs in the 4πM-H curve, residual induced magnetization 4πMr, intrinsic coercivity Magnetic iHc.Among them, the coercivity (Hc) can be used as the separation of soft magnetic and hard magnetic materials. When the coercivity is less than 20 Oersted (Oe), the material belongs to soft magnetic; the coercivity >200 Oersted (Oe) When , the material belongs to hard magnetic or permanent magnet; and when 20 < coercive force < 200 Oersted (Oe), the material belongs to semi-hard magnetic.A good permanent magnet material must have high Br, Hc, iHc, (BH)max and Curie temperature (Tc), low irreversible temperature coefficient, better mechanical strength and weather resistance and other characteristics.In the field of rare earth permanent magnets in China, Spin Technology Corp., located in Hukou, Hsinchu, has been developing rare earth magnets (SmCo / NdFeB) in the Magnetic Group of ITRI since 1982. The Institute of Materials of the Research Institute (now the Institute of Materials and Chemicals) has transferred technology and built a factory to produce Sintered NdFeB Magnet and Bonded NdFeB Magnet production technology.Since 2004, Sumin Technology has applied for a total of 9 patents related to the layout of rare earth magnets, 6 of which are inventions and 3 are new types (Figure 2). The current legal status is shown in Figure 3.Analysis of its International Patent Classification (IPC) is mostly H01F 1/057, that is, the rare earth metal alloy hard magnetic materials with the characteristics of group IIIa elements (such as Nd2Fe14B) are the most.The use of pure rare earth elements to make magnets has excellent magnetic properties, but because pure rare earth elements are quite expensive, the cost is relatively increased.In order to reduce the cost of using rare earth elements to make hard magnetic materials, and to make the magnetic properties reach the standard of commercial magnetic powder, it also has a soft magnetic phase and a hard magnetic phase.Sumin Technology applied for a patent for a dual-phase nanocrystalline hard magnetic material containing mixed rare earth, which is composed of a composition represented by (YaLabCecPrdNde)xFe100-xyz-uCoyXzBu in atomic percentage, within the scope of its claimed patent application (Claims) Among them, YaLabCecPrdNde is restricted to be mixed rare earth and an intermediate product of rare earth element extraction process, so as to avoid the problem of high cost caused by the use of pure rare earth elements in the past; the scope of patent rights will also be a+b+c≦0.6; d+e≧0.4; x=7~11at%; y=0~5at%; z=0.1~3at%; and 8at%The rare earth elements referred to in the patent are light rare earth elements (Light Rare Earth Elements, LREE), which refer to scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), titanium ( Pr), neodymium (Nd), strontium (Pm), samarium (Sm) and europium (Eu), and X is such as titanium (Ti), vanadium (V), niobium (Nb), hafnium (Hf), chromium (Cr) ), zirconium (Zr), molybdenum (Mo), tungsten (W) and other refractory elements.Using YaLabCecPrdNde mixed rare earth as the source of rare earth elements to replace pure rare earth elements can reduce the amount of pure rare earth elements and save a lot of raw material costs on the premise of achieving the magnetic properties of commercial magnetic powder.In addition, the dual-phase nanocrystalline hard magnetic material includes two crystalline phases, a soft magnetic phase and a hard magnetic phase. By improving the exchange coupling effect between the soft and hard magnetic phases, the residual magnetization (Br) and the magnetic energy product ((BH) can be increased. max), and provide a suitable intrinsic coercivity (iHc).U.S. patent practice requires evidence based on relevant citations, a person with general knowledge in the field, a motivation to modify/combine the prior art, and a reasonable expectation of success , in order to assert that the request item is not progressive.And this motivation can be overturned through some negative evaluations in the citation case, the so-called teach away, but it is worth thinking about "what kind of evaluation can be considered negative?"