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The Synthesis of Iron Aluminide Nano Composite/Alumina by in Situ Procedure Based on Mechanical Alloying and Surveying Some of its Mechanical Characteristics

Fareghi, Arash | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40520 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Purazaang, Kazem; Salahi, Esmail
  7. Abstract:
  8. In this study, first nano structure powders of Fe3AL / Al2o3 by different percentages of reinforcement phases (10, 20 and 50 percent of volume) based on mechanical milling procedure was created. To do so, iron, Al and iron oxide (hematite) pure powder based on special weight percentages mixed with each other and milled in 20 to 100 hour periods based on two different weights of ball toward powder: 10 and 20. Morphological variations, particles sizes and powder densities, lattice strain and phase variations in different timing periods of mechanical milling process was studied by Scanning Electron Microscopy(SEM) , analyzing apparatus of particles sizes by laser , gaseous picnometer and X-ray diffractometry in different timing periods and also micro structure variations of samples was studied. By surveying the results of these tests, it was found that the milling of pure powders for 40 hours and for powders with 10 and 20 percent of reinforcement phase volume and 60 hours for powder with 50 percent of volume from reinforcement phase and with weight percentage of 20 for ball toward powder to synthesize composite powders is suitable. The grain size of samples after milling reached to less than 50 nanometers. Then pressure behavior of powders in different pressures was studied and it was showed based on pressure equations. After that the strength of powders was estimated. It became clear that the addition of strength phase caused the reduction of pressure in composite powders. To supply dense composite samples, the mixture of supplied composed powders becomes out of gas and aniling, and then they were surveyed to determine the two step sintering . After surveying 3 different heating processes based on density and the final grain size , heating process in the following levels was suitable : T1= 1200 and T2= 1100. The density of final samples was between 93 till 96 percent and the size of grain size of composites was less than 100 nanometers. At the final part of this study, the pressure reinforcement behavior and three points strength of environment temperature of composite samples was studied. By comparing the results it was found that by increasing reinforcement phase the level of strength and pressure strength increases and the level of 3point bending strength decreases.


  9. Keywords:
  10. Tron Aluminide ; Alumina ; Nanocomposite ; Mechanical Milling ; Tree Point Strength ; Two Step Sintering ; Pressure Strength

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