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An Investigation on in-situ Synthesis and Wear Behavior of Al-Al3Ti Nanocomposite Produced via Mechanical Alloying/Hot-Press Technique

Hejazi Dehaghani, Mohammad Mehdi |

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39123 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Maddah Hosseini, Hamid Reza
  7. Abstract:
  8. In the present investigation, the mechanical alloying (MA) technique was employed to produce nanocrystalline Al-Ti alloys. Elemental Al and Ti powders were mixed with different compositions (0, 5, 10, and 20 wt.% Ti) and then, milled in a planetary ball-mill up to 40 h. The variations of powder morphology and particle size, apparent and tap densities, microstructure, grain size, lattice strain, and microhardness were studied with increasing the milling time. While dissolution of Ti in the Al matrix resulted to the formation of supersaturated Al-Ti solid solution in the samples containing 5 and 10 wt.% Ti, the specimen with 20 wt.% Ti, eventually, led to nanocomposite powder with different types of titanium aluminide reinforcements, at the end of milling operation. The grain size of all samples tended to the values of lower than 40 nm, after 5 h milling. The changes in apparent and tap densities were found to be in accordance with morphological evolution during the MA process. Then, the milled powders were subjected to hot-press technique to produce Al-Al3Ti nanocomposites. The dry-sliding wear behavior of nanocomposites samples was studied and it was found that mild oxidative mechanism was the dominant wear mechanism. In Al-20Ti specimen, delamination mechanism was also activated. The wear resistance of Al-Al3Ti nanocomposites enhanced by increasing the Ti amount (volume fraction of Al3Ti reinforcing particles), which can be attributed to the increase in sample hardness, and formation of a mixed oxide layer of Al2O3-TiO2 on the worn surface
  9. Keywords:
  10. Mechanical Alloying ; Wear Resistance ; Hot Press ; Titanium Aluminide ; Aluminum Matrix Nanocomposite

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