The effect of tungsten addition on the magnetic properties and microstructure of SmFeN–α-Fe nanocomposites

Waldemar Kaszuwara , Marcin Leonowicz , J.A Kozubowski

Abstract

The effect of tungsten addition, in the range of 0–17 at.\%, on the magnetic properties and microstructure of SmFeN–α-Fe permanent magnet nanocomposites is presented. The magnets were prepared by mechanical alloying of elementary powders of Sm, Fe and W, followed by annealing and nitriding. The addition of tungsten leads to initial increase and further decrease of the coercivity with a maximum value of 250 kA/m for 7 at.\% W. The remanence, however, continuously decreases from 1.2 T for 0\% W down to 0.7 T for 17 at.\% W. The maximum value of (BH)max, (120 J/m3), was obtained for 2 at.\% W. The measurements of Curie temperature vs. W content showed a constant and decreasing values for α-Fe and the Sm2Fe17 phase, respectively. This behaviour can be explained by the dissolution of some W atoms in the Sm2Fe17 phase. X-ray diffraction analysis indicated, beside the α-Fe and Sm2Fe17 phases, the existence of pure W in the microstructure. Addition of W leads to reduction of the α-Fe crystallite size (20 nm for 0\% W, 18 nm for 7\% W and 8 nm for 17\% W). The high resolution electron microscopy investigations show randomly distributed small (below 20 nm) crystallites of tungsten. Thus for a small amount of W the remanence is still substantially enhanced. The increase of the coercivity, for W contents up to about 7 at.\%, can possibly be attributed to increased magnetic anisotropy of the Sm2(Fe,W)17N3 phase.
Author Waldemar Kaszuwara (FMSE / DCFM)
Waldemar Kaszuwara,,
- Division of Construction and Functional Materials
, Marcin Leonowicz (FMSE / DCFM)
Marcin Leonowicz,,
- Division of Construction and Functional Materials
, J.A Kozubowski - [Warsaw University of Technology (PW)]
J.A Kozubowski,,
-
- Politechnika Warszawska
Journal seriesMaterials Letters, ISSN 0167-577X
Issue year2000
Vol42
No6
Pages383-386
Keywords in Englishmagnetic properties, Microstructure, SmFeN–αFe, Tungsten
ASJC Classification2210 Mechanical Engineering; 2211 Mechanics of Materials; 3104 Condensed Matter Physics; 2500 General Materials Science
DOIDOI:10.1016/S0167-577X(99)00215-3
URL http://www.sciencedirect.com/science/article/pii/S0167577X99002153
Score (nominal)35
Score sourcejournalList
Publication indicators WoS Citations = 5; Scopus Citations = 9; GS Citations = 11.0; Scopus SNIP (Source Normalised Impact per Paper): 2000 = 0.75; WoS Impact Factor: 2006 = 1.353 (2) - 2007=1.822 (5)
Citation count*11 (2015-04-25)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
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