Magnetic materials
Microstructure and magnetic properties of neodymium permanent magnets
We are analyzing the microstructure of neodymium permanent magnets, currently called the strongest permanent magnets, using electron microscopy to improve their magnetic properties. Coercive force, an indicator of the stability of a magnet's performance, is an indispensable property for the continued safe use of permanent magnets. However, the "coercive force mechanism," or what factors cause this coercive force, has been the subject of much debate, but it remains unclear. Our laboratory is working to elucidate this coercive mechanism using the latest electron microscopy techniques.
For example, neodymium magnets are used in motors for automobiles and drones because they must be compact and powerful. The interior of a neodymium magnet is composed of small Nd2Fe14B grains and several phases called grain boundary phases that span between the grains. Various microstructural factors, such as the distribution, shape, composition, and orientation of these phases, have a complex effect on the properties. Therefore, it is becoming increasingly important to elucidate what kind of microstructure is necessary for high properties through electron microscopic analysis.
