Amorphous nanocrystalline magnetic cores, due to their excellent soft magnetic properties, are widely used in the high-power medium and high-frequency transformers, high-frequency switching power supplies, electromagnetic compatibility components, high-precision current transformers, as well as magnetic sensors and other devices in the fields of national defense, military industry, and civilian electric power electronics. However, domestically produced high-performance amorphous nanocrystalline magnetic cores mainly rely on imports, with foreign products being expensive and subject to strict technological secrecy, which severely restricts the development of related national defense and civilian technologies in China. The superior magnetic properties of amorphous nanocrystalline magnetic cores originate from their unique amorphous nanocrystalline structure. Traditional amorphous nanocrystalline magnetic core manufacturing techniques cannot effectively control the microstructure of the magnetic core material, and high-performance cores have not yet been produced. This project has lasted nearly 10 years, supported by the National 863 Program, Shanghai Municipal Science and Technology Commission's Nanometer Special Project, etc., starting with the study of the nanocrystallization mechanism of magnetic cores, overcoming key manufacturing technology challenges, Develop high-performance amorphous nanocrystalline magnetic cores and realize the industrialization of magnetic cores. The main work and innovative achievements are as follows: 1. Considering that the nanocrystallization process of amorphous nanocrystalline magnetic cores is a complex dynamic process of temperature-sensitive multi-step crystallization superposition, a kinetic model for studying the nanocrystallization mechanism of amorphous alloy by non-isothermal method was constructed, and the nanocrystallization mechanism of typical amorphous alloys was elucidated. Based on this, key preparation technologies for the nanocrystallization of amorphous nanocrystalline magnetic cores were established, providing a reliable theoretical foundation and technical support for the optimization of key heat treatment processes in the large-scale production of amorphous nanocrystalline magnetic cores; 2. Addressing the problems of high frequency loss and low inductance of conventional magnetic core heat treatment with common mode inductor cores, a composite magnetic field heat treatment technology was established, and amorphous nanocrystalline magnetic cores with high saturation magnetization intensity and initial permeability were developed, realizing the industrialization of high-performance common mode inductor magnetic cores; 3. In response to the problem of sudden temperature rise in magnetic cores during the nanocrystallization process due to crystallization exothermicity, which leads to deteriorated core performance and poses a challenge for mass production, a heat treatment technology has been established that uses a heat absorber to reduce the temperature increase caused by crystallization exothermicity, thereby achieving industrialization of amorphous nanocrystalline current transformers' magnetic cores; 4. To address issues such as low filling factor, high internal stress, and susceptibility to breakage in conventional amorphous transformer cores, two types of amorphous core winding equipment and fixtures have been designed and developed, and a longitudinal external magnetic field heat treatment process for transformer cores has been established. Amorphous cores with good performance have been successfully prepared, along with transformers. Compared to national standards, the no-load loss of the produced amorphous transformers has been reduced by 12.5%, and the load loss by 7.4%; 5. By utilizing magnetron sputtering and electroplating methods, magnetic cores with giant magnetoresistance effects exceeding 800% have been prepared, successfully applied in fields such as automotive electronic sensors and non-destructive testing. This project has broken through the key preparation technology for the industrialization of amorphous nanocrystalline magnetic cores. Through the development of magnetic core materials, understanding of the nanocrystallization mechanism, and optimization of the large-scale production process, high-performance amorphous nanocrystalline magnetic cores with independent intellectual property rights have been developed, achieving industrial application of nanocrystalline magnetic cores. The project's achievements have been evaluated by experts as being novel and innovative, with related technologies reaching the international advanced level. 11 invention patents have been applied for, with 4 granted; 33 SCI-indexed papers have been published, including 6 in top 5 journals in the field of metal and metallurgical engineering. Some of the achievements have been industrialized by Shanghai Micrometallic Electric Appliance Co., Ltd., and successfully applied in both national defense and civilian fields. Famous companies such as Siemens, Shanghai Electric and related military units have used our products. In the past five years, this project has added 120 million yuan in new output value and 17.84 million yuan in new profits, achieving good economic benefits. Through the implementation of this project, it has promoted the technical level of power electronic device development and application in China's defense and civilian fields, reduced dependence on foreign imported products, enhanced national defense and civilian scientific and technological strength, supported the implementation of the country's energy conservation and emission reduction strategy, and contributed to the development of national defense and the economy and society.