TY - JOUR
T1 - Effect of Co Content on the Structure and Magnetic Properties of Melt-Spun Fe55-xCoxPt15B30 Alloys
AU - Ma, Dianguo
AU - Wang, Yingmin
AU - Yubuta, Kunio
AU - Li, Yanhui
AU - Zhang, Wei
N1 - Funding Information:
Supported by National Natural Science Foundation of China (Nos.51571047 and 51171034).
Publisher Copyright:
© All right reserved.
PY - 2017/5/11
Y1 - 2017/5/11
N2 - Fe-Pt-B nanocomposite magnets have attracted much attention because of their excellent hard magnetic properties, in which the face-centered-tetragonal FePt (L10) phase ensures high coercivity (iHc) and the Fe2B phase provides high magnetic saturation. A high iHc, however, is hard to reach at low Pt concentrations in these nanocomposite magnets. It is known that a high concentration of B favors the formation of L10 phase in Fe-Pt-B alloys with low Pt concentration, but the annealed microstructure is usually coarse-grained due to their low amorphous-forming abilities, and the magnetic properties get deteriorated. Replacement of Fe with Co is expected to enhance the amorphous-forming ability of Fe-Pt-B alloys with low Pt and high B concentrations, and to improve their magnetic properties. In this work, the structure and magnetic properties of as-quenched and annealed Fe55-xCoxPt15B30 (x=0~45, atomic fraction, %) alloys have been investigated. Melt-spun ribbons were prepared by melt spinning, followed by vacuum annealing at different temperatures. The structure and magnetic properties of the samples were examined by XRD, TEM and a vibrating sample magnetometer (VSM). The results indicate that single amorphous phase is formed in the alloys at x=15~45. After appropriate annealing, a nanocomposite structure consisting of L10 and (Fe, Co)2B phases is obtained at x=0 and 15, and an additional (Fe, Co)B phase gets formed at x=30 and 45. A fine microstructure with mean grain size of ~18 nm has been obtained in the annealed alloys with x=15~45. In these nanocomposite alloys, the best hard magnetic property with an energy product of 94.4 kJ/m3 is reached at x=15. With increasing Co content, the iHc gradually increases to a maximum value of 413.7 kA/m at x=30, and then decreases at higher Co contents, which are attributed to the change of the magnetocrystalline anisotropy in L10 phases with different c/a ratios.
AB - Fe-Pt-B nanocomposite magnets have attracted much attention because of their excellent hard magnetic properties, in which the face-centered-tetragonal FePt (L10) phase ensures high coercivity (iHc) and the Fe2B phase provides high magnetic saturation. A high iHc, however, is hard to reach at low Pt concentrations in these nanocomposite magnets. It is known that a high concentration of B favors the formation of L10 phase in Fe-Pt-B alloys with low Pt concentration, but the annealed microstructure is usually coarse-grained due to their low amorphous-forming abilities, and the magnetic properties get deteriorated. Replacement of Fe with Co is expected to enhance the amorphous-forming ability of Fe-Pt-B alloys with low Pt and high B concentrations, and to improve their magnetic properties. In this work, the structure and magnetic properties of as-quenched and annealed Fe55-xCoxPt15B30 (x=0~45, atomic fraction, %) alloys have been investigated. Melt-spun ribbons were prepared by melt spinning, followed by vacuum annealing at different temperatures. The structure and magnetic properties of the samples were examined by XRD, TEM and a vibrating sample magnetometer (VSM). The results indicate that single amorphous phase is formed in the alloys at x=15~45. After appropriate annealing, a nanocomposite structure consisting of L10 and (Fe, Co)2B phases is obtained at x=0 and 15, and an additional (Fe, Co)B phase gets formed at x=30 and 45. A fine microstructure with mean grain size of ~18 nm has been obtained in the annealed alloys with x=15~45. In these nanocomposite alloys, the best hard magnetic property with an energy product of 94.4 kJ/m3 is reached at x=15. With increasing Co content, the iHc gradually increases to a maximum value of 413.7 kA/m at x=30, and then decreases at higher Co contents, which are attributed to the change of the magnetocrystalline anisotropy in L10 phases with different c/a ratios.
KW - Amorphous alloy
KW - Crystallization
KW - L1-FePt phase
KW - Magnetic property
KW - Nanocomposite magnet
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U2 - 10.11900/0412.1961.2016.00485
DO - 10.11900/0412.1961.2016.00485
M3 - Article
AN - SCOPUS:85026250321
VL - 53
SP - 609
EP - 614
JO - Jinshu Xuebao/Acta Metallurgica Sinica
JF - Jinshu Xuebao/Acta Metallurgica Sinica
SN - 0412-1961
IS - 5
ER -