Title page for etd-0727113-150811


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URN etd-0727113-150811
Author Hsin-wei Lin
Author's Email Address No Public.
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Department Materials and Optoelectronic Science
Year 2012
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Study on Mechanical Properties of Electrodeposited Ni and Ni-Co alloys with Microstructure
Date of Defense 2013-07-29
Page Count 109
Keyword
  • mechanical properties
  • bimodal size distribution
  • nickel
  • nickel-cobalt
  • electrodeposition
  • Abstract This work aims at clarifying the effect of post-deposition annealing on the mechanical properties of Ni and Ni-Co samples prepared by electrodeposition. The Co content of the Ni-Co samples is 15wt% and 40 wt%, respectively. The microstructure was characterized by scanning electron microscopy, electron backscattering diffraction and transmission electron microscopy. Tensile tests showed that the strength of the samples decreased with increasing the annealing temperature. The ductility, on the other hand, increased with the annealing temperature. However, the strength of the sample annealed at 240 or 260 oC was very similar to that of the 220 oC annealed one, whereas the ductility of the former increased. Accordingly, the strength-ductility product of the 240 oC- or 260 oC- annealed samples increase from the regular value of 8-11 GPa to 13GPa%. Similar phenomenon has not been observed for the Ni-Co samples. Microstructure analyses indicated that the dislocation density in the grain interior decreased associated with slight growth of grains after anneal. An obvious bimodal distribution of grain size was found for the 240 oC- or 260 oC- annealed samples with 35-40 vol.% of coarse grains. The volume ratio of the coarse grains is less than 20 % after the ni-Co samples were annealed at the same temperatures. Accordingly, grains having a bimodal size distribution improves the ductility of the sample if the volume ratio of the coarse grains reach a critical value.
    Advisory Committee
  • Der- shin Gan - chair
  • New-Jin Ho - co-chair
  • Jui-Chao Kuo - co-chair
  • Liu-wen Chang - advisor
  • Files
  • etd-0727113-150811.pdf
  • Indicate in-campus at 5 year and off-campus access at 5 year.
    Date of Submission 2013-08-27

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