Title page for etd-0710108-154048


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URN etd-0710108-154048
Author Chen-wei Tang
Author's Email Address No Public.
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Department Materials Science and Engineering
Year 2007
Semester 2
Degree Master
Type of Document
Language English
Title Mechanical Properties and Micro-Forming Ability of Au-Based Bulk Metallic Glasses
Date of Defense 2008-07-04
Page Count 150
Keyword
  • Au-based BMG
  • amorphous
  • mechanical properties
  • Abstract The mechanical properties and micro-forming of the Au-based bulk metallic glasses are reported in this thesis. The original ingots were prepared by arc melting and induction melting. The Au49Ag5.5Pd2.3Cu26.9Si16.3 bulk metallic glasses with different diameters 2 and 3 mm were successfully fabricated by conventional copper mold casting in an inert atmosphere. By the observation of transmission electron microscopy diffraction pattern, there are crystalline phases among the amorphous matrix phase.

    The Au49Ag5.5Pd2.3Cu26.9Si16.3 bulk metallic glass shows the high glass forming ability and good thermal stability. By the Differential scanning calorimetry (DSC) results, the values ofΔΤx and ΔΤm are 50 and 21 K. And Trg, γ, and γm values for the Au49Ag5.5Pd2.3Cu26.9Si16.3
    bulk metallic glass (BMG) at the heating rate of 0.67 K/s are 0.619, 0.430 and 0.774,
    respectively.
    The mechanical properties of Au49Ag5.5Pd2.3Cu26.9Si16.3 in terms of compression testing
    are examined using an Instron 5582 universal testing machine. Room temperature
    compression tests are conducted on specimens with various strain rates. To know the size
    effect, the micro-pillars were made by using a focus ion beam (FIB) technique. The
    micro-pillars were under the tests of compression at different strain rates, compared with
    macro-scale 2 mm rod specimens. In contrast to the brittle fracture in a bulk sample, these
    micro-pillar specimens show significant plasticity. The morphology of compressed pillar
    samples indicates that the number of shear bands increased with the sample size and strain rates.
    Advisory Committee
  • Cheng-tang Pan - chair
  • Shian-ching Jang - co-chair
  • Chih-Ching Huang - advisor
  • Files
  • etd-0710108-154048.pdf
  • indicate access worldwide
    Date of Submission 2008-07-10

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