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Investigation on the Influence of Cooling Rate on Microstructure of CuCr25% Melt-spun Alloy

Nadi Mobarakeh, Elham | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45758 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Varahram, Nasser; Davami, Parviz
  7. Abstract:
  8. The Cu-Cr10% ingots were prepared in induction furnace and these ingots were used to prepare CuCr25% in VAR. The percentages of elements were checked by chemical analysis. The ingots were divided to slices with 20gr mass and these slices were put in quartz tubes. The quartz tubes were assembled in melt spinning machine and the ribbons were quenched onto a rotating copper wheel. Three different wheel speeds, 8, 16, 36 m/s were chosen. The microstructure of the ribbons was examined using a scanning electron microscopy (SEM). The relationship between wheel speed and thickness of the ribbons were compared with mathematical modeling. The disk of ribbons with thickness of 0.5mm and radius of 5mm were made with cold pressing by using 5tons force. These disks were used to investigate the electrical properties of ribbons. In order to investigate the influence of heat treatment, the electrical resistance of the disks was examined by using LCR machine after and before sintering them in 800 ˚C. The results indicated the difference in microstructure, between two sides of ribbons at the wheel speed of 8m/s and 16m/s because the cooling rate is different in these two sides. At the wheel speeds of 36 m/s the microstructure contained fine spherical precipitated particles. The investigation on electrical resistance before and after heat treatment, showed the influence of second phase on electrical resistivity
  9. Keywords:
  10. Melt Spinning ; Microstructure ; Cooling Rate ; Ribbons Alloy

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