Abstract
The microstructure of explosively compacted Nd-Fe-B alloys has been investigated by means of transmission electron microscopy and X-ray diffraction. It is shown that there are three kinds of phases, i.e. the matrix phase Nd 2 Fe 1 4 B, O-rich phases and Nd-rich phases in explosively compacted Nd-Fe-B magnets. The matrix Nd 2 Fe 1 4 B phase is tetragonal, with lattice parameters of a = 0.88 nm and c = 1.22 nm. The O-rich phase was present at the two-grain boundary and three-grain junctions, with the fcc structure, and the lattice parameter is a = 0.559 nm. The O-rich phase belongs to the compound Nd-Fe-O, and the contents of O, Nd and Fe are 45-60 at%, 20-40 at% and 10-21 at%, respectively. It is also shown that a large number of block-shaped Nd-rich phases are in a two-grain boundary or three-grain junctions or Nd 2 Fe 1 4 B phase, with the hcp structure and the lattice parameters of a = 0.395 nm and c = 0.628 nm. The Nd-rich phases belong to compound Nd-O, and the contents of Nd and O are 80-85 at% and 10-15 at%, respectively. Also a few dislocations in the boundary phase have been observed.
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