• Title/Summary/Keyword: Ultrafine Grains

Search Result 32, Processing Time 0.016 seconds

INFLUENCE OF B AND Nd CONTENT ON THE MAGNETIC PROPERTIES OF ${\alpha}-Fe$ BASED NdFeB MAGNETS WITH ULTRAFINE GRAINS

  • Cho, Y.S.;Kim, Y.B.;Park, W.S.;Kim, C.S.;Kim, T.K.
    • Journal of the Korean Magnetics Society
    • /
    • v.5 no.5
    • /
    • pp.427-431
    • /
    • 1995
  • The influence of Nd and B contents on the magnetic properties and structures of ${\alpha}-Fe$ based Nd-(Fe,Co)-B-Mo-Cu alloys was investigated. $Nd_{4}{(Fe_{0.9}Co_{0.1})}_{92-x}B_{x}Mo_{3}Cu_{1}$ and $Nd_{x}{(Fe_{0.9}Co_{0.1})}_{86-x}B_{10}Mo_{3}Cu_{1}$ amorphous alloys prepared by rapid solidification process were crystallized to form nanocrystalline structure. The increase of B content in $Nd_{4}{(Fe_{0.9}Co_{0.1})}_{92-x}B_{x}Mo_{3}Cu_{1}$ nanocrystalline resulted in the change of stucture of soft phase in the sequence of ${\alpha}-Fe$->${\alpha}-Fe+Fe_{3}B$->$Fe_{3}B$. The coercivitis of the alloys were increased with increasing B content and was 263 kA/m at x=18. On the contrary, the remanence has shown an opposite trends. The increase of Nd content in $Nd_{x}{(Fe_{0.9}Co_{0.1})}_{86-x}B_{10}Mo_{3}Cu_{1}$ nanocrystalline containing ${\alpha}-Fe$ as main phase had no effect on the structure and improved coercivity up to 256 kA/m. However, the remanence was decreased from 1.4 T to 1.15 T according to the increase of Nd content.

  • PDF

Synthesis of Nanostructured Si Coatings by Hybrid Plasma-Particle Accelerating Impact Deposition (HP-PAID) and their Characterization (하이브리드 플라즈마 입자가속 충격퇴적(Hybrid Plasma - Particle Accelerating Impact Deposition, HP-PAID) 프로세스에 의한 Si 나노구조 코팅층의 제조 및 특성평가)

  • 이형직;권혁병;정해경;장성식;윤상옥;이형복;이홍림
    • Journal of the Korean Ceramic Society
    • /
    • v.40 no.12
    • /
    • pp.1202-1207
    • /
    • 2003
  • Using a recently developed Hybric Plasma-Particle Accelerating Impact Deposition (HP-PAID) process, synthesis of nanostructured silicon coatings has been investigated by injecting vapor-phase TEOS (tetraethosysilane, (C$_2$H$\_$5/O)$_4$Si) into an Ar hybrid plasma. The plasma jet with reactants was expanded through nozzle into a deposition chamber, with the pressure dropping from 700 to 10 torr. Ultrafine particles accelerated in the free jet downstream of the nozzle, deposited by an inertial impaction onto a temperature controlled substrate. By using this process, nanostructured amorphous silicon coatings with grain size smaller than 10 nm could be synthesized. These samples were annealed in an Ar and crystallized at 900$^{\circ}C$ for 30 min. TEM analysis showed that the annealed coatings were also composed of nanoparticles smaller than 10 nm, which showed a good consistency that the average grain size of 7 nm was also estimated from a peak shift of 2.39 cm$\^$-1/ and Full Width at Half Maximum (FWHM) 5.92 cm$\^$-1/ of Raman analysis. The noteworthy is that a strong PL peak at 398 nm was also obtained for this sample, which indicates that the deposited coatings also contained 3∼4 nm nanostructured grains.