Title :
Coercivity and spin reorientation transitions in Nd-Fe-B nanocomposites prepared by melt spinning
Author :
Dahlgren, M. ; Kou, X.C. ; Grössinger, R. ; Liu, J.F. ; Ahmad, I. ; Davies, H.A. ; Yamada, Koji
Author_Institution :
Inst. fur Exp. Phys., Vienna Univ. of Technol., Austria
fDate :
5/1/1997 12:00:00 AM
Abstract :
Alloys of composition Nd9Fe85B6, Nd11.76Fe82.46B5.88, and Nd18Fe76B6 were prepared by melt spinning at roll velocities from 19 to 25 m/s. The grain size distribution of rapidly quenched flakes was evaluated by means of X-ray diffraction line broadening. The average grain size of rapidly quenched Nd-Fe-B alloys is within a range from 19 to 40 nanometers and differs from the roll contact side to the free side of the flakes. For the first time, the spin reorientation transitions TST of nanophase Nd 2Fe14B alloys have been determined. They were found to be lower than that of bulk Nd2Fe14B. The smaller the grain size, the lower is TST. Also for the first time, the temperature dependence of the coercivity of nanophase Nd-Fe-B magnets was determined from 4.2 to 300 K by measuring hysteresis loops on a single flake in a pulsed-field magnetometer with a field strength up to 24 MA/m. The coercivity of the nanophase Nd-Fe-B has less of a temperature dependence than sintered magnets
Keywords :
X-ray diffraction; boron alloys; coercive force; ferromagnetic materials; grain size; iron alloys; magnetic anisotropy; magnetic hysteresis; magnetic transitions; melt spinning; nanostructured materials; neodymium alloys; permanent magnets; rapid solidification; spin dynamics; 19 to 25 m/s; 19 to 40 nm; 4.2 to 300 K; Nd-Fe-B nanocomposites; Nd11.76Fe82.46B5.88; Nd18Fe76B6; Nd9Fe85B6; X-ray diffraction line broadening; coercivity; grain size distribution; hysteresis loops; magnetic anisotropy; melt spinning; nanophase Nd-Fe-B magnets; nanophase Nd2Fe14B alloys; pulsed-field magnetometer; rapidly quenched flakes; roll velocities; spin reorientation transitions; temperature dependence; Coercive force; Grain size; Iron alloys; Magnetic field measurement; Magnets; Neodymium; Pulse measurements; Spinning; Temperature dependence; X-ray diffraction;
Journal_Title :
Magnetics, IEEE Transactions on
