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Fatigue Behavior of Al-SiC Nanocomposite

Ghasemi Yazdabadi, Hassan | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42371 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Simchi, Abdolreza; Ekrami, Ali Akbar
  7. Abstract:
  8. Recently, mechanical properties of advanced materials such as nanostructured and ultra-fine materials and especially nanocomposites were studied by lots of researcher. In this study, fatigue behavior of Al-SiC nanocomposites is observed. Ultra-fine grains Al matrix nanocomposites reinforced with 50 nm diameter SiC nanoparticles were produced by milling and hot extrusion. For this purpose, pure aluminum powder was mixed with 2, 4 and 6 Vol. % of SiC nanoparticles and then milled by planetary mill. The milled powder then were degased in an Argon atmosphere furnace, cold pressed and then hot extruded. Closed die-hot forging was used with about 18.8% reduction in cross section in order to enhance the extruded billet’s density. The hot forged billets then were cut to the flat shape samples based on the ASTM E466 & E606 standards. Fatigue tests were conducted in pull-pull mode with the minimum to maximum stress ratio of 0.1, using a frequency range of 1-40 Hz. It was shown that the addition of nanoparticles to the matrix enhance the fatigue strength at 107. Fatigue lives at higher stress levels than the yield strength was higher for the unreinforced matrix comparing to the nanocomposites. It is also shown that increasing the nanoparticles content in the nanocomposites further improve the fatigue strength. Fractography by Scanning Electron Microscopy revealed a ductile fracture in the final fracture region of fatigued fracture surfaces in presence of hard nanoparticles to the matrix
  9. Keywords:
  10. Nanocomposite ; Fatigue ; Ultra-Fine Grain Materials ; Aluminum-Silicon Alloy

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