Dissertation > Excellent graduate degree dissertation topics show

Phase Field Simulation of Grain and Precipitate Evolution under Gradient Field

Author: YouYuan
Tutor: ZuoMuFu
School: Harbin Institute of Technology
Course: Materials Science
Keywords: Temperature field Concentration field Grain Precipitated phase Phase field simulation
CLC: TG111.5
Type: Master's thesis
Year: 2008
Downloads: 75
Quote: 0
Read: Download Dissertation

Abstract


In this paper, the phase-field method to study the phase evolution of the gradient field of grain and precipitation . Based on the Ginzburg - Landau theory of phase transitions ( Ginzburg - Landau ) to derive the low volume fraction of grain evolution of the temperature gradient field phase precipitation and concentration gradient field precipitated phase by phase-field model . Two sets of space vector representation of the original grain and recrystallized grains , grain phenomenological parameter coupling temperature field , the establishment of a temperature gradient grain phase-field model , to achieve a uniform temperature field and gradient temperature field evolution of the value analog . The results showed that the recrystallization volume fraction are phenomenological parameters αa reduced increase ; average grain size with the gradient factor kappaB increases . 17-4PH steel after heat treatment cycle , the average grain size gradually decreases with increasing number of cycles . 17-4PH steel laser surface hardening , formed on the specimen surface layer gradient grain . The cycle thermal insulation and laser surface hardening of grain evolution in modeling, simulation and experimental results . Based on the Cahn-Hilliard equation , modified local free energy function in the highest powers of concentration field variables , broadening the precipitated phase volume fraction range , the phase-field model of the low volume fraction precipitation process . In the model, the coupling grain space vector square and exponential items (Σηi2) μ, consider the impact of the grain boundary phase precipitation process . Phase precipitates to achieve a low volume fraction of solute volume fraction of less than 5% of the numerical simulation . The results showed that the grain space vector sum of squares of exponent decision of the second phase is precipitated at the grain boundaries intragranular proportion to increase in the intragranular precipitation phase proportion with the decrease in μ value , precipitated phase sizes vary depending on the concentration field gradient The energy coefficient κφ ; the mu = or larger κφ of precipitation concentrated in the grain boundaries . 20 Steel and A3 Steel 560 ° C plasma rare earth Nitrocarburizing to show that the gamma ' phase showed a gradient , surface needle- gamma ' phase and long, along the permeation layer Gamma ' the phase gradually reduced and shorter . The coupled free energy , interfacial energy and elastic strain energy , the establishment of a concentration gradient field Evolution of precipitated phase phase-field model . Pair of parallel the permeation surface and along the permeation layer in the gamma ' phase precipitation process was simulated , the simulation results consistent with the experimental results .

Related Dissertations

  1. Study on Contact Fatigue Life Based on Grease Variation with Temperature,TH117.22
  2. Simulation Analysis on Temperature Stress of RCC Arch Dam and Its Construction Joints Design Research,TV642.2
  3. Analysis and Study of Abutment Stability in Concrete High Arch Dam by Three-Dimensional Nonlinear Finite Element Method,TV642.4
  4. The Study on the Location and Level of Grain Market in Peking during Republican China Period,K291
  5. Study on the Mechanism of Night Temperature to Grain Filling of Inferior in Rice,S511
  6. The Evolvement of Quartzs and Phytoliths in Basalt-Derived Chronosequence Soils in Tropics Area of China,S153
  7. Mineralogical and Geochemical Evidence of the Presence of Ancient Paddy Soil Layer in Chuodun Ancient Agricultural Site, Kunshan,S-09
  8. Effects of Seeding Stage on Source-Sink Relation in a Ratoon Rice Cropping System with Labor Reduced Cultivation in Northearstern Jiangxi Province,S511
  9. Difference in Development between Culm and Tiller Roots and Their Contribution to Grain Yield and Quality in Wheat (Triticum Aestivum L.),S512.1
  10. Effect of Wheat Straw Wood Vineger on Grain Yield and Qualities of Rice,S511
  11. Predicting Wheat Grain Yield and Quality Based on Population Indexes and Nitrogen Nutrient Status,S512.1
  12. Effects of Different Models of Cultivation Management on Nitrogen and Carbon Metabolism and Grain Yield in Winter Wheat,S512.1
  13. Study on the Regulatory Effects of Nitrogen Application Period on Yield Formation and Quality with Wheat,S512.1
  14. Radiation Transfer Characteristics and Radiation Use Efficiency of Rice,S511
  15. Effects of Cultivation Methods and Row Spacing on Yield Formation and Proportionality of Ningjing 3,S511.22
  16. Effects of Nitrogen Application Rates on Root Growth and Distribution and Grain Yield of Winter Wheat,S512.11
  17. Research on the Physiology Mechanism of Grain Filling of inferior Grain during Day and Night Chemical Regulations,S511
  18. QTL Analysis of Grain Filling Rate and Associated Traits in Maize,S513
  19. Quantifying the Response of the Grain Quality of Wheat to DIM Light at Filling Stage,S512.1
  20. Method of Stored Grain Pest Control in Rural Areas,S379
  21. Effects of Nitrogen Fertilization on Winter Wheat in Mid Henan Under High-Yielding Condition,S512.1

CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallurgy ( Physical Metallurgy ) > Physics of metals > Metal solid -phase structure and phase transition
© 2012 www.DissertationTopic.Net  Mobile