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Title page for etd-0813112-181405


URN etd-0813112-181405 Statistics This thesis had been viewed 1154 times. Download 1 times.
Author Yu-Ta Cheng
Author's Email Address No Public.
Department Materials Engineering
Year 2011 Semester 2
Degree Master Type of Document Master's Thesis
Language zh-TW.Big5 Chinese Page Count 109
Title Optimization of Key Factors Controlling the Refinement of Primary Silicon in a Hyper-eutectic Al-Si Alloy
Keyword
  • AlP
  • Refinement
  • Primary Silicon
  • Hyper-eutectic Al-Si Alloy
  • Hyper-eutectic Al-Si Alloy
  • Primary Silicon
  • Refinement
  • AlP
  • Abstract In this research the refinement of primary silicon in hyper-eutectic Al-Si alloys were studied. The reason of refinement fading and the way to avoid it were also studied. A variety of key variables which have profound influences on the refinement of primary silicon were examined, which include P content, melt holding temperature and time, and the method to take melt samples. The results show that only by homogeneous nucleation can fine precipitates of AlP be produced from the alloy melt. And these fine AlP precipitates act as nucleus of primary silicon for proper refinement. When there are coarse pre-existed AlP particles present in alloy melt, heterogeneous nucleation takes place and results in very limited amount of AlP particles. Consequently, this results in a poor refinement of primary silicon. It was found from the optimization of refinement control that, in the range of P content from 60 to 120 ppm and melt temperatures from 720 to 780 oC, alloy melts with less P content and higher melt temperature exhibit better refining effect. It was also found that by proper refinement treatment the particle size of primary silicon can be reduced to 30 um or less. In which case, the distribution of primary silicon would be very uniform and the Si-depletion ratio was found to be less 12%.
    Advisor Committee
  • Chih-Fu Yang - advisor
  • none - co-chair
  • none - co-chair
  • none - co-chair
  • Files indicate in-campus access at 2 years and off-campus not accessible
    Date of Defense 2012-07-23 Date of Submission 2012-08-14


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