Title :
Structural studies of some hydrogen-treated materials related to the HDDR-process of Nd2Fe14B-based alloys
Author :
Uehara, M. ; Choi, P. ; Tomida, T. ; Tomizawa, H. ; Hirosawa, S. ; Maehara, Y.
Author_Institution :
Sumitomo Special Metals Co. Ltd., Osaka, Japan
fDate :
11/1/1995 12:00:00 AM
Abstract :
Hydrogen-treated Nd14.0Fe66.9Co11.0 Ga1.0Zr0.1B7.0 alloys have been examined by means of powder X-ray diffraction (XRD) and electron probe microanalysis (EPMA) to understand the mechanism of the development of magnetic anisotropy in the hydrogenation, decomposition, desorption, and recombination (HDDR) process of Nd2Fe14B-based alloys. It has been revealed that Nd2Fe14B phase can coexist in equilibrium with decomposed products, namely, α-Fe, NdH2, and Fe2B, in the presence of hydrogen of an atmospheric pressure over the temperature ranging 1113 to 1153 K. It was observed that Co and Ga condensed into a Nd2Fe14B phase during hydrogen-treatments, resulting in a thermodynamically stable Nd2(Fe,Co,Ga)14B compound. Well-developed anisotropic materials were obtained via the HDDR-process when the hydrogen-treatment was accomplished under such conditions that Nd2 (Fe,Co,Ga)14B coexists with the decomposed products. All our results give a favorable support to the previous proposal that the crystallographic orientation of the original alloy can be conveyed via the undecomposed Nd2Fe14B particles through-out HDDR processing
Keywords :
X-ray diffraction; boron alloys; cobalt alloys; coercive force; crystal microstructure; electron probe analysis; ferromagnetic materials; gallium alloys; iron alloys; magnetic anisotropy; neodymium alloys; permanent magnets; remanence; zirconium alloys; 1113 to 1153 K; Nd14.0Fe66.9Co11.0Ga1.0 Zr0.1B7.0; Nd2Fe14B-based alloys; crystallographic orientation; decomposition; desorption; electron probe microanalysis; hydrogenation; magnetic anisotropy; powder X-ray diffraction; recombination; thermodynamically stable Nd2(Fe,Co,Ga)14B; Cobalt alloys; Electrons; Gallium alloys; Iron alloys; Neodymium; Powders; Probes; X-ray diffraction; X-ray scattering; Zirconium;
Journal_Title :
Magnetics, IEEE Transactions on