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The Effect of Mn on Microstructure and Mechanical Properties on Splat Cooled Al-20Si-5Fe-3Cu-1Mg Alloy

Moazzeni Pour, Pooyan | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40177 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Davami, Parviz
  7. Abstract:
  8. In this research ,Al-20Si-5Fe-3Cu-1Mg-XMn alloys were produced by gas atomizing and melt spinning processes. Microstructure and growth morphology of powder and ribbons were investigated using optical microscopy , scanning electron microscopy. powders were hot pressed at 400ºC/250Mpa and microstractural variations, mechanical properties were evaluated after consolidation. Results show that relatively high cooling rate in gas-atomized powders lead to refinement of microstructure and formation of semi-equilibrium δ intermetallic phase . As the powder particle size decrease , the growth morphology changes from primary silicon + euthectic to euthectic + primary dendritic aluminum . Mn changed the morphology of δ-intermetallic compound and refined the size of primary silicon. In melt-spun ribbons, two different zones (featureless with faceted growth morphology and dendritic) were observed. Higher cooling rate in ribbons compared to powder extended solid solubility of alloying elements and suppressed the formation of any intermetallic phases. After hot consolidation, solubility of silicon and alloying elements at the matrix decreased and consequently, coarsening of Si and precipitation of iron intermetallic compound in nanometric scale observed. Results of mechanical testing showed higher mechanical strength of melt-spun ribbons compared to the atomized powders, particularly at elevated temperatures.

  9. Keywords:
  10. Aluminum-Silicon Alloy ; Rapid Solidification ; Mechanical Properties ; Morphology ; Growth

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