爆炸压结Nd-Fe-B永磁体微观结构

Grain-Boundary Structure of Explosively Compacted Nd-Fe-B Magnets

摘要:

利用透射电镜、X射线衍射仪、X射线能谱仪，对爆炸压结Nd-Fe-B永磁合金进行微观组织结构的观察和分析。结果表明：爆炸压结Nd-Fe-B的组织主要由基体Nd2Fe14B相、富O相和富Nd相组成；基体相是硬磁相，四方晶体结构，其晶格常数为a=0．88nm和c=1．22nm；富O相形貌呈三角状或层状，分布在3个晶粒交隅处和两个晶粒交界处，其晶体结构均为面心立方（fcc），点阵常数a=0.559nm；富Nd相呈不同块状形貌，镶嵌存基体内或晶界上，其晶体结构为密排六方（hcp），晶格常数a=0．395nm和c=0.628nm：在富O相中O，Nd和Fe的含量（原子分数，下同）分别为45％～60％，20％～40％和10％～12％，块状富Nd相中则为80％～85％Nd和10％～l5％O，同时还发现晶界相中分布着少量的位错。

Abstract:

The microstructure of the explosively compacted Nd-Fe-B permanent magnets has been investigated by means of TEM and XRD. It is shown that there are three kinds of phases: matrix Nd2Fe14B, O-rich phases and Nd-rich phase with different structures and compositions in explosively compacted Nd-Fe-B permanent magnets. Matrix Nd2Fe14B is predominantly the hard Nd2Fe14B phase with lattice parameters of a=0.88 nm and c=1.22 nm. The O-rich phase presented at the two-grain boundaries and three-grain junctions, with fcc structures, and lattice parameter is a=0.559 nm. The O-rich phase belong to the compound Nd-Fe-O, and contents of O, Nd and Fe are 56at%, 22at% and 21at%, respectively. It is also shown that a large number of the block-shaped Nd-rich phases are in the two-grain boundary or three-grain junctions or Nd2Fe14B phases, with hcp structure and lattice parameters of a=0.395 nm and c=0.628 nm. The Nd-rich phases belong to compound Nd-O, and contents of Nd and O are 85at% and 12at%, respectively. Also a few dislocations in the boundary phases have been observed.