MSE Test2

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MSE Test2
2012-10-14 18:44:19

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  1. mixture
    more than one phase
  2. solution
    one phase
  3. phase
    a physically and chemically destinct material region
  4. simple system
    both elements have same crystal structure, similar electro neg, and atomic radii
  5. binary
    2 components
  6. isomorphous
    complete solubility of one component in another
  7. Eutectic
    liquid transforms into two solid phases
  8. eutectiod
    solid phase tranforms into two different solid phases
  9. peritectic
    • liguid and one solid phase transform into another solid phase
    • L + S1 to S2
  10. ferite
  11. cementite
  12. hyper and hypo eutectoid steel
    • hyper > .76% C
    • hypo < .76% C
  13. elastic deformation
  14. plastic deformation
  15. tensile stress
    σ = Ft/A0
  16. shear stress
    T = Fs/A0
  17. torsion
    a form of shear stress
  18. bi-axial tension
    • force in 4 directions
    • ex. pressurized tank
  19. hydrostatic compression
    force is same in all directions
  20. tensile strain
    ε = δ/L0
  21. Lateral Strain
    εL = −δ L/W0
  22. Shear strain
    γ = Δx/y = tanθ
  23. hookes law
    σ = E ε
  24. Modulus of elascticity
  25. True stress
    σT = F/Ai
  26. True Strain
    εT = ln (Li/Lo)
  27. Toughness
    • Energy needed to break a unit volume of material
    • hammer test in lab
  28. Ductilty
    the plastic strain at failure
  29. Ductile Fracture
    • Accompanied by significant plastic deformation
    • one piece, large deformation
  30. Brittle Fracture
    • little or no plastic deformation
    • many Pieces
    • small deformations
  31. intergranular
    between grains
  32. transgranular
    through grains
  33. fatigue
    failure under applied cyclical stress
  34. creep
    strain vs time 
  35. slip plane
    • plane on which easiest slippage occurs
    • highest planar density
  36. Slip direction
    • Direction of easiest slip movement
    • highest linear density
  37. isotropic
    same properties in all directions
  38. anisotropic
    properties depends on direction
  39. 4 ways to strengthen
    • reduce grain size
    • form solid solution
    • -remove defects
    • Percipitation strengthening
    • -put different material in such as ceramic to combat shear strain
    • Cold work
    • -strain hardening
    • -room temp
    • -cold forming reduces cross sectional area
  40. 3 stages of heat treatment
    • Recovery
    • -reduction of disolacation density by annihilation
    • -atoms diffuse to form perfect atomic planes
    • Recrystalization
    • -new grains formed with lower dislocation density
    • Grain grown
    • -change grain size based on rate of cooling
  41. Cold working
    deformation below TR
  42. Hot working 
    Deformation above TR
  43. Grain size influence
    • small = strong and tough at low temps
    • large = good creap resistance at high temps
  44. Why plastic deformation occurs at stresses that are much smaller than the theoretical strength of perfect crystals?
    Force needed for plastic deformation is much smaller than the force needed to break allbonds within the slip plane. This is where dislocations play a significant role to explain thisobservation. To cause large movement in the slip plane is not necessary to break all bonds ofthe particular plane but rather involve large number of dislocations or you can think of aspropagation of a dislocation.
  45. TR
    recrystallization temperature = temperature at which recrystallization just reaches completion in 1 h.