Microstructure of explosively compacted Nd-Fe-B magnet by TEM
(Key Laboratory for High Temperature Materials and Tests, Ministry of Education, Shanghai Jiaotong University, Shanghai 200030, China)
Abstract: The microstructure of an explosively compacted Nd-Fe-B permanent magnet(Nd-Fe-B) was investigated by means of TEM and XRD. It is shown that there are three kinds of phases: Nd2Fe14B matrix phase, O-rich phases and Nd-rich phase with different structures and compositions in the magnet. The hard magnetic phase Nd2Fe14B is tetragonal, which lattice parameters are determined to be a=0.88nm and c=1.22nm. The O-rich phase locates at the grain boundaries and the triple junctions has fcc structure whose lattice parameter is a=0.559nm. A dislocation is observed in this phase. It is also found that a large number of the block-shaped Nd-rich phases with hcp structure are embedded in the Nd2Fe14B matrix or at grain boundary. Their lattice parameters are determined to be a=0.395nm and c=0.628nm.
Key words: explosively compacted Nd-Fe-B; microstructure; boundary phase