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Structure and Magnetic Properties of Melt Spun and Sintered Sm(Co,Cu,Fe,Zr,M)_z(M=C,Cnts)Magnet

Author: ZhangWei
Tutor: SunJiBing
School: Hebei University of Technology
Course: Materials Science
Keywords: rare-earth permanent melt-spun crystallization annealing sintering andaging magnetic properties
CLC: TM273
Type: Master's thesis
Year: 2011
Downloads: 43
Quote: 0
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Abstract


SmCo matrix permanent magnetic materials of TbCu7-type have been widely studiedbecause of their potential application as high temperature permanent magnets. In this paper,carbon nanotubes （CNTs） were added into the permanent magnet alloy ofSm0.116Co0.607Cu0.061Fe0.187Zr0.027. Sm（Co,M）7 ribbons with TbCu7-type structure wereprepared by rapid-quenching and crystallization annealing processes. And Sm2Co17-typesintered magents were prepared by powder metallurgy process. Using x-ray diffractometer,scanning electronic microscope, vibrating sample Magnetometer, the effects of carbonaddition, melt-spun process, crystallization annealing, sintering and aging process on themicrostructure and magnetic properties of bulk alloys and ribbons were studied.It was found that carbon or CNTs additions didn’t change the phase structure ofSm0.118Co0.607Cu0.061Fe0.187Zr0.027 as-cast alloy, however, they changed the phase content andphase distribution in the alloy. Moreover, the carbon or CNTs addition improves thecoercivity of as-cast alloys.In order to get high performance sintered magnets, an ideal process route is as follow,the balls and alloys occupy about 50% volume of the whole ball-milling pot and their massratio is 10:1 while themass tatio of balls of different diameters isφ14:φ12:φ10:φ8:（φ5+φ6）=17:17:22:22:22 （wt%）. The main influencing factors that affected most areorientation of magnetic powder andresidual ball-milling mediums and oxygen content andhomogenized degree of compositionThe cast sintered Sm0.118Co0.607Cu0.061Fe0.187Zr0.027 magnet obtains its magnetic propertiesare sa follows, Hci=26105Oe，Mr=74.5emu/g，M2T=79.8emu/g when it is sintered at 1200°Cand then aged at 830°C. While the ones of melt-spun ribbons sintered magnet by progressesabove are Hci=10147 Oe，Mr=53.8emu/g，M2T=74.5emu/g. TheSm0.118Co0.607Cu0.061Fe0.187Zr0.027 bonded magnet possess better magnetic properties withHci=2326Oe，Mr=45.7emu/g，M2T=93.9 emu/g when the melt-spun speed is 40 m/s.

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CLC: > Industrial Technology > Electrotechnical > Electrical materials > Magnetic materials,ferrite > Permanent magnet materials, permanent magnet
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