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Title page for etd-0824106-174142


URN etd-0824106-174142 Statistics This thesis had been viewed 1401 times. Download 8 times.
Author Yan-Dong Cheng
Author's Email Address No Public.
Department Materials Engineering
Year 2005 Semester 2
Degree Master Type of Document Master's Thesis
Language English Page Count 115
Title Preparation and Analysis of Co-based Amorphous Powders by Mechanical Solid-state Reaction
Keyword
  • coercive force
  • saturation magnetization
  • soft magnetic properties
  • supercooled liquid region temperature
  • amorphous
  • amorphous
  • supercooled liquid region temperature
  • soft magnetic properties
  • saturation magnetization
  • coercive force
  • Abstract This research investigated amorphisation and soft magnetic properties of Co-based alloy powers synthesized by solid-state high-energy ball milling. The crystal structures and microstructures of the milled amorphous powders were determined. The thermal behavior of the product was determined by measuring their glass transition temperature and crystallization temperature. The magnetic properties of the synthesized powders were measured by using a SQUIT device. For the ternary Co-Ti-B system, amorphous powders can be obtained from all the powder mixtures after being milled for a certain period of time. Among all the ternary compositions, Co70Ti25B5 exhibits maximum supercooled liquid region of 64 oC. Quaternary Co70-XMXTi25B5 (M=Nb, Fe) system was adopted to reduce Co by replacing some of the Co with Nb or Fe element. The powder mixtures in this system, after being milled for a certain period of time, can also produce amorphous phase. The results indicated that, in terms of thermal stability (based on the supercooled liquid region temperature) and soft magnetic properties (based on the saturation magnetization and coercive force), the overall performance of quaternary Co70-XNbXTi25B5 is superior to the Co70-XFeXTi25B5 system. The alloy with composition of Co55Nb15Ti25B5 has been shown to exhibit superior amorphous property with supercooled liquid region of 65 oC. The alloy with composition of Co45Nb25Ti25B5 powder has been shown to exhibited optimal soft magnetic properties with saturation magnetization Bs of 0.013 T and coercive force Hc of 3.4 A/m.
    Advisor Committee
  • Hsin-Ming Wu - advisor
  • none - co-chair
  • none - co-chair
  • Files indicate in-campus access only
    Date of Defense 2006-07-24 Date of Submission 2006-08-24


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