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用TEM观察了烧结NdFeB永磁合金的内边界显微结构,发现该合金存在4种类型的边界。回火前后前三类边界的形貌没有变化,而第4类边界的显微结构发生了显著的变化。用SAED和AES分析了第4类边界的成分与结构,该边界由两个区域组成,即富Nd相区和Nd_2Fe_(14)B晶粒的外延层。回火时,由于原子的扩散和物质迁移,Nd_2Fe_(14)B晶粒的外延层发生了磁硬化,因而合金的矫顽力得到提高。
TEM observation of the sintered NdFeB permanent magnet alloy inner boundary microstructure and found that the alloy there are four types of boundaries. The morphology of the first three types of boundary before and after tempering did not change, while the microstructure of the boundary of type 4 changed significantly. The composition and structure of the boundary of the fourth type were analyzed by SAED and AES. The boundary was composed of two regions, that is, the epitaxial layer of Nd-rich phase and Nd 2 Fe 14 B crystal. During tempering, due to the diffusion of atoms and the material migration, the Nd 2 Fe 14 B crystallite epitaxial layer is hardened, so the coercive force of the alloy is improved.