烧结NdDyFeB磁体加热过程中的热力学与动力学现象

The Analysis of Thermodynamic and Kinetic Phenomena of Sintered NdDyFeB Magnets in Heating Process

从热力学的角度分析了NdDyFeB磁体加热各阶段中微观组织的转变过程,研究了这个过程中所发生的质点重排、固溶沉淀、固相骨架形成、形态多边化等动力学现象。结果表明,显微结构的变化,将引起密度的变化,进而导致磁性能的变化。富Nd液相的存在,晶粒表面气体吸附膜的排除,晶粒间存在的化学位差均有利于磁体向致密化方向发展。晶粒粗化,形态多边化和孔洞排出是获得最终致密度的关键。

The developing processes of microstructure of NdDyFeB green compacts in the different heating stages have been analysed in a thermodynamic principle, and some kinetic phenomena such as particle rearrangement, solution-precipitation, formation of solid skeleton and ploygonization have also been researched. It is shown that the density of magnets varies with the change of microsturcture, leading to the change of magnetic properties. The presence of Nd-rich liquid phase, the elmination of gas absorbed film on the surface of grains of different sizes are helpful for densification of magnets. The grain coarsing, polygnonization of grain shape and pore migration are keys to obtain the final densification.