Title :
Detailed TEM analysis of solid-HDDR Nd16Fe76B 8 magnetic materials
Author :
Matzinger, M. ; Fidler, J. ; Gutfleisch, O. ; Harris, I.R.
Author_Institution :
Inst. of Appl. & Tech. Phys., Tech. Univ. of Vienna, Austria
fDate :
11/1/1995 12:00:00 AM
Abstract :
Detailed microstructural characterization was carried out by means of transmission electron microscopy on a Nd16Fe76B 8 alloy during various stages of a S(Solid)-HDDR process (T=800°C, p(H2)=0.7 bar). The disproportionated, colony-type matrix consists of parallel aligned NdH-2 cylinders of submicron size, embedded in an α-Fe matrix. There is a crystal orientation relationship within each colony: NdH2 {100}||α-Fe{100}, NdH2<001>||α-Fe<001>. Grains of Fe2 B with an average size of 100 nm show planar crystal defects and are randomly distributed within the matrix. The recombination starts with a coarsening process in each colony. In an early recombined Nd2Fe14B matrix, remaining spherical Nd-rich and α-Fe regions were found. Further vacuum annealing leads to a refined Nd2Fe14B matrix with some remaining α-Fe inclusions. Due to Nd diffusion from the grain boundaries into the disproportionated regions, some Nd-rich material can be found at the triple points of the recombined Nd2Fe14B grains
Keywords :
annealing; boron alloys; crystal microstructure; desorption; ferromagnetic materials; grain boundaries; iron alloys; magnetic particles; neodymium alloys; permanent magnets; transmission electron microscopy; 0.7 bar; 800 C; HDDR-materials; Nd16Fe76B8; TEM; coarsening; colony-type matrix; crystal orientation; grain boundaries; microstructure; planar crystal defects; recombination; triple points; vacuum annealing; Grain boundaries; Hydrogen; Iron; Magnetic analysis; Magnetic materials; Monitoring; Neodymium; Powders; Temperature; Transmission line matrix methods;
Journal_Title :
Magnetics, IEEE Transactions on
