Effect of elements on the magnetic properties, phase evolution, and microstructure of SmCo7 type nanocomposite ribbons
| Autor: | Shih-Teng Huang, 黃世騰 |
|---|---|
| Rok vydání: | 2006 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 In recent years, alloys consist of SmCo7 phase have drawn much attention, because it possesses high magnetic anisotropy field of about 90 kOe. In the study, we adopt SmCo7 as the base alloy for melt spinning to prepare the ribbons under sufficient supercooling condition. At first, Hf and Zr elements were adopted to substitute for Co in the SmCo7-xTx (x=0-0.5) ribbons for stabilizing SmCo7 phase. The σr and iHc of the ribbons increased with the increment of substitution ratio for M=Hf or Zr. The optimal magnetic properties of Br=6.4 kG, iHc=7.3 kOe and (BH)max=8.7 MGOe were achieved in SmCo6.9Hf0.1 ribbons. Next, Ti, B, C and Cu were added in the SmCo6.9Hf0.1M0.1 ribbons for further improving the microstructure of the ribbons. A slight addition of Ti, B and C in SmCo6.9Hf0.1M0.1 ribbons was found to refine the microstructure of the ribbons effectively, except for Cu addition. The optimal grain size of 10-50 nm were achieved in SmCo6.8Hf0.2C0.12 nanocomposites. Furthermore, for SmCo7-xHfxCy (x=0.1-0.3, y=0-0.14) series ribbons, the addition of a slight C substitution could enhance the σr and (BH)max. But when C content y is over 0.14, 1:5, 2:17, 2:7 and Sm2C3 phases appeared, iHc was decreased accordingly. The optimal magnetic properties of Br=6.9 kG, iHc=11.8 kOe and (BH)max=10.6 MGOe were achieved in SmCo6.8Hf0.2C0.12 nanocomposites. Final, this research also tried to substitute Co with Fe in attempts to increase the magnetic properties of the aforementioned ribbons. Partial substitution of Co with Fe did give rise to an increase of σs with a sacrifice of iHc. However, the improved magnetic properties of Br=8.4 kG, iHc=6.1 kOe and (BH)max=12.4 MGOe were achieved in Sm(Co0.8Fe0.2)6.8Hf0.2C0.12 nanocomposites. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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