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The Study of Microstructure and Phase Transformations in MP210 Superalloy

Abouali, Sara | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41123 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Asgari, Sirous
  7. Abstract:
  8. MP210 alloy is a member of multiphase family alloys, a class of wrought nickel-cobalt base alloys extensively used in high-quality applications including aerospace fasteners, gas turbine engines and petrochemical industry. Very limited information can be found in the literature about the microstructure and phase transformations of this alloy. The aim of this work is characterizing the aging response of the material and identifying the major strengthening phases precipitated in different range of temperatures and also studying the static recrystallization behavior of this alloy. The effect of age-hardening heat-treatment on the microstructure of MP210 superalloy was investigated using hardness testing, optical microscopy, X-ray diffraction, scanning and transmission electron microscopy. All of the samples were solution-treated at 1100C for 1 h and aged in the temperature range of 600C to 1000C for 1, 2 and 3 h. The alloy showed an impressive age-hardening response and it was found that the major strengthening phase in this alloy is Gamma prime ( ) with L12 structure. The results also approved the formation of Eta (η) phase in the temperature range of 925 degree C to 1000 Degree C throughout the matrix. The recrystallization behavior of MP210 is investigated by means of hardness testing, optical microscopy, scanning and transmission electron microscopy. It is found that the alloy resists recrystallization up to a high temperature of 1025°C. Recrystallized grains are readily formed at grain boundaries below this temperature; however, the growth of these new grains is inhibited by and η precipitates having coherent facets with the nickel matrix (γ). The passage of the recrystallization front results in coherency loss and consequently dissolution of the and η platelets. Recrystallization proceeds with a discontinuous precipitation of the η phase behind the moving boundary
  9. Keywords:
  10. Sedimentation ; Recrystallization ; MP210 Superalloy

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