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Production of Nanostructured Soft Magnetic Composites via Mechanical Alloying and Warm Compaction

Mohseni, Farzin | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43987 (07)
  4. Department: Materials Science and Engineering
  5. Advisor(s): Madaah Hosseini, Hamid Reza; Shokrollahi, Parvin
  6. Abstract:
  7. In this investigation, effect of processing parameters on the soft magnetic properties of nanocrystalline Fe85Si10Ni5 (at. %)-phenolic resin composites were studied. The nanostructured powders were obtained by mechanical milling in a high-energy vibratory disc mill. Annealing was performed to decrease internal strains and density of dislocations. The microstructure, morphology and DC magnetic properties of the milled powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and a vibrating sample magnetometer (VSM). Bulk samples were obtained by compaction in different pressures and temperatures. The effects of different compaction treatments and annealing treatment of bulk samples on structural, electrical and AC magnetic properties of compressed samples have been investigated by SEM, inductance capacitance resistance (LCR) meter, and calculation of density and electrical resistivity. The results show that the Fe(Si-Ni) solid solution is formed after 180 min milling. The powders were annealed under argon atmosphere at 500, 550 and 600 °C for 1 h. The amounts of lattice strain for different samples were calculated by Williamson–Hall method. The powders that have not experienced annealing treatment have higher residual stresses and higher coercivity. Increase of annealing temperature decrease the hysteresis loss and coercivity of milled powders. Also, results indicate that with warm compaction and increasing compaction pressure till 600 MPa, AC magnetic properties, Density and electrical resistivity of bulk samples noticeably increase and then show small changes. Although, annealing treatment of bulk samples at 170 °C for 1 h causes little decrease of samples density, it noticeably increases electrical resistivity
  8. Keywords:
  9. Warm Compaction ; Mechanical Alloying ; Nanostructured Soft Magnetic Composites (NSMC) ; Direct Current (DC)Magnetic Properties ; Alternative Current (AC)Magnetic Properties

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