Title :
The influence of Ga-substitution on the coercivity of Nd-(Fe,Co)-B sintered permanent magnets
Author :
Fidler, Josef ; Groiss, Claudia ; Tokunaga, M.
Author_Institution :
Inst. of Appl. & Tech. Phys., Tech. Univ. Vienna, Austria
fDate :
9/1/1990 12:00:00 AM
Abstract :
In Co-substituted Nd-Fe-B sintered magnets, several additional phases such as Nd(Fe,Co)yB? with y=2, 3, and 4 have been found besides the hard magnetic phase and the Nd-rich intergranular phase. The low coercivity of the magnet is attributed to the occurrence of these soft ferromagnetic phases. In Ga-doped Nd-(Fe,Co)-B sintered magnets, new intergranular phases such as Nd(Ga,Fe,Co) and Nd(Ga,Fe,Co)2 have been found instead of the soft ferromagnetic Co-rich phases. From X-ray microanalysis data it is concluded that Ga substitutes the transition-metal atoms in the 2:14:1-phase, and Ga is not detected in the Nd-rich phase at all. The increase of the coercivity of Ga-doped magnets is correlated to a higher volume fraction of intergranular phases and an increased wetting during sintering due to these phases
Keywords :
X-ray chemical analysis; boron alloys; cobalt alloys; coercive force; ferromagnetic properties of substances; gallium alloys; iron alloys; neodymium alloys; permanent magnets; sintering; transmission electron microscope examination of materials; Nd-Fe-Co-B-Ga; X-ray microanalysis; analytical TEM; coercivity; energy dispersive X-ray spectra; hard magnetic phase; intergranular phases; optical metallography; sintered permanent magnets; soft ferromagnetic phases; transition-metal atoms; transmission electron microscopy; wetting; Coercive force; Electron microscopy; Magnetic analysis; Magnetic force microscopy; Neodymium; Permanent magnets; Phase detection; Physics; Temperature; Transmission electron microscopy;
Journal_Title :
Magnetics, IEEE Transactions on
