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Fabrication of AZ91/ SiCp Composite In Semi-Solid State By Using Electromagnetic Stirring, Microstructures And Mechanical Properties

Ghaderi, Mohammad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51570 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Aashuri, Hossein
  7. Abstract:
  8. In this study AZ91 alloy reinforced by SiC particles processed by semi-solid casting was produced by using electromagnetic stirrer. In order to prevent ignition and oxidation of the melted AZ91 alloy 1 Wt.% of calcium was added to the melt. In order to surface oxidation of SiC particles, they were heat treated in 1100 ᵒC for 2 hours before adding to the melt. Different methods of adding SiC particles to the melt were investigated. Particle distribution in the matrix was studied qualitatively and quantitatively using microscopic images and image analysis, respectively. It is shown that higher amount of reinforcement particle need to be added to the melt in multi-steps. Frequency versus inter particle spacing (IPS) diagrams were obtained and used to compare distribution of SiC particles. It was shown that adding 10 Wt.% of SiC particles in two-step had the lowest deviation from random and uniform distribution which was 18% and 10%, respectively. It was also shown that by increasing the amount of reinforcement particles, chart range of frequency versus inter particle diagrams was limited. Composites which were produced by adding 10 Wt% SiC particles in two-steps, had the lowest chart range and ratio of the chart range was 1.25 of the chart range of random distribution. Clustering parameters in composites containing 2.5, 5 and 10 Wt.% SiC particles were measured and were compared to wear rates. Composites with the best particle distribution had the highest wear resistance and it was illustrated that improvement of wear behavior in the sliding distance of 1000 meter and force of 63 N was more sensible than lower sliding distances and forces. Wear rate in composites with 2.5 Wt.% of SiC particle in the above mentioned wear conditions was reduced 19% compared to the base alloy and in composites which were produced by adding 10 Wt.% SiC particles in two-steps in wear conditions of 100-meter distance and 63 N force was reduced 33% compared to base alloy. Hardness of the samples increased by adding more SiC particles and improvement of particle distribution caused reduction in hardness variation in each sample
  9. Keywords:
  10. Metal Matrix Composite (MMC) ; Semi-Solid Casting ; Wear ; Cluster Control Parameters ; Electromagnetic Stirrer ; Interparticle Spacing ; Aluminum-Magnesium Reinforced Silicon Carbide Alloye (AZ31/Sicp)

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