Title :
The disproportionation of Nd2Fe14B under hydrogen in Nd-Fe-B alloys
Author :
Book, D. ; Harris, I.R.
Author_Institution :
Sch. of Metall. & Mater., Birmingham Univ., UK
fDate :
9/1/1992 12:00:00 AM
Abstract :
The kinetics of the disproportionation reaction in which the Nd 2Fe14B phase forms Fe, Nd-hydride, and Fe2 B under hydrogen has been investigated by thermopiezic analysis. These studies have shown that the disproportionation temperature is dependent on grain size, and is considerably lower for Nd-Fe-B alloys with submicron grain sizes when compared with the case material. Thus, melt-spun material disproportionates at a temperature about 300°C below that of cast alloy (at a heating rate of 1°C/min). In addition, the amount of Nd2Fe14B phase in the alloy can be related to the temperature range over which the reaction occurs and to the amount of Fe and Fe2B that forms as a result of the disproportionation reaction. The latter can be monitored by measuring the magnetization of the disproportionated material
Keywords :
boron alloys; dissociation; ferromagnetic properties of substances; grain size; iron alloys; magnetisation; neodymium alloys; permanent magnets; reaction kinetics; thermal analysis; H2 atmosphere; Nd-Fe-B alloys; Nd2Fe14B; cast alloy; disproportionation reaction kinetics; disproportionation temperature; grain size; magnetization; melt-spun material; thermopiezic analysis; Grain size; Heating; Hydrogen; Iron alloys; Kinetic theory; Magnetic materials; Monitoring; Neodymium; Temperature dependence; Temperature distribution;
Journal_Title :
Magnetics, IEEE Transactions on
