Search and Control of optimal grain boundary structure in NdFeB magnetic materials by novel electron microscopy technique

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Multi-scale microstructure analysis of four kinds of Nd-Fe-B magnetic materialswere investigated by novel electron microscopy technique, and the following fiveresearches were carried out : 1. Development of nanostructure analysis technique connected directly with macro-scale magnetic structure, 2. Role of Tb element in the Tb-vaporsorption treated Nd-Fe-B sintered magnet, 3. Additive elements and coercivities in the PLD thick-film magnets, 4. Grain boundary structures and coer civities in the HDDR magnet powders, 5. Changes in microstructure and coercivity in the hydrogenated sintered magnets. One of notable results is to find the existence of ultra-thin grain boundary amorphous(GB) phase surround each Nd2Fe14B grain, and the thin GB phase contributes greatly to the generation of coereivity in Nd-Fe-B magnetic materials.