MICROSTRUCTURES AND MAGNETIC-PROPERTIES OF FE-PT PERMANENT-MAGNETS

Citation
Y. Tanaka et al., MICROSTRUCTURES AND MAGNETIC-PROPERTIES OF FE-PT PERMANENT-MAGNETS, Journal of magnetism and magnetic materials, 170(3), 1997, pp. 289-297
Citations number
13
Categorie Soggetti
Material Science","Physics, Condensed Matter
ISSN journal
03048853
Volume
170
Issue
3
Year of publication
1997
Pages
289 - 297
Database
ISI
SICI code
0304-8853(1997)170:3<289:MAMOFP>2.0.ZU;2-5
Abstract
We have investigated the magnetic properties of Fe-38.5Pt, Fe-39.5Pt a nd Fe-50.0Pt (at %) alloys after various heat treatment conditions usi ng a vibrating sample magnetometer, and correlated these properties wi th the microstructures of the alloys by transmission electron microsco py. The Fe-50Pt ahoy shows poor magnetic hardness regardless of the he at treatment conditions. The magnetic hardness of the Fe-39.5Pt alloy shows a maximum value after annealing for 10 h at 873 K, while it mono tonically decreases after annealing at 1073 K. The alloy with the high est coercivity was composed of a single phase gamma(1) with an average domain size of approximately 10 nm. The electron diffraction results indicate that the alloy is frustrated with accumulated stress, induced by a cubic --> tetragonal transformation which occurs without twinnin g. On the other hand, when stress is relieved by twin formation after prolonged aging, the coercivity decreases. By annealing at 1073 K, the well known polytwin structure evolves. However, only poor hard magnet ic properties are observed when this polytwin structure appears, Hence , the highest coercivity is attributed to the formation of nanoscale L 1(0) ordered antiphase domains which is expected to be a highly anisot ropic single domain magnetic particle.