MSE 250 test1

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Anonymous
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172235
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MSE 250 test1
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2012-09-20 17:44:44
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MSE
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test 1 flash cards
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  1. amorphous
    • No long range order
    • Possible short range order
    • not periodic
  2. crystalline
    • long range order
    • position repeated over and over
  3. Atomic packing factor
    • vol of atoms in cell / cell volume
    • n*4/3*pi*R^3/a^3
    • n= number or atoms in unit cell
    • relate a and R to solve using geometry bases on sc,bcc, or fcc
  4. superstitual impurity
    lattice site taken up by another element
  5. vacancy
    lattice site missing atom
  6. self interstitual
    same element not on a lattice site
  7. impurity interstitual
    another element not on a lattice site
  8. two dislocations or line defects?
    edge and screw dislocations
  9. 4 point defects?
    • vacancy
    • self interstitual
    • impurity interstitual
    • superstitual impurity
  10. coordination #
    • number of nearest neighbors
    • bcc = 6
    • bcc = 8
    • fcc = 12
  11. Theoretical density
    • P = (n*A)/(Vc*Na)
    • n = number of atoms/cell
    • A= atomic weight
    • Vc = a^3 = volume of unit cell
    • Na = avagadros number
  12. rank densities of materials in general
    • metal
    • ceramics
    • polymers, composites
  13. isotropic
    • uniform crystal structure
    • equiaxed
  14. Anisotropic
    • crystal structure not uniform in all directions
    • lenticular and irregulararly oriented
  15. Polymorph
    single element material changes its structure as a function of temp
  16. alatroph
    when a compound changes its structure as a function of temp
  17. Planar density
    # of atoms centered on a plane / area of plane
  18. Linear density
    # of atoms centered on direction vector/ length of dir. vector
  19. equixed
    • uniform grain boundries
    • strong
  20. lenticular/columnar
    • elongated grain boundries
    • not as strong as equiaxed
  21. Intrinsic
    Natural property of material
  22. extrinsic
    man controlled property
  23. Quantum numbers
    • n = energy shell level (1 2 3 4..)
    • l  = orbitals (s p d f)
    • Ml = magnetic or number of electrons in orbital*2 (1 3 5 7) 
    • Ms = spin (+-1/2)
  24. Bond energy
    En = Er + Ea = -A/r + B/rn
  25. ionic covalent mixed bonding equation
    1 - (e^((Xa-Xb)^2/4))*100%

    • Xa and Xb are elements electronegativity
    • only good for mixtures of two elements
  26. primary bonding
    matallic, ionic and covalent
  27. secondary bonding
    dipole - dipole or vand er waals
  28. metallic bonding
    material shares/ floats electrons as a whole. barely covered...
  29. covalent bonding
    sharing electrons
  30. ionic
    giving and recieving electrons creating charged atoms that then are attracted to eachother.
  31. alpha
    coefficient of thermal expansion
  32. Tm
    melting temperature
  33. E0
    bond energy
  34. ceramic
    • large E0
    • large Tm
    • small alpha
    • brittle, glassy
    • non conductors
  35. metals
    • moderate Tm
    • moderate E0
    • moderate alpha
    • high thermal and electrical conductivity
    • strong ductile
  36. polymers
    • small E0
    • small Tm
    • large alpha
    • soft, ductile
    • thermal and electrical insulators
  37. Solidification
    Result of casting of molten material
  38. Equilibrium concentration of point defects
    Nv/N = e^(-Qv/kT)

    • Nv = no of defects
    • N = no of potential defect sites
    • Qv = activation energy
    • k = boldamins constant
    • T =temperature
  39. substitutional solid solution conditions
    • atmoic radius difference less than 15%
    • proximity in periodic table/similar electro neg
    • same crystal structure for pure metals
    • Valancey - a metal will be more likely to disolve element of higher valancey than lower.
  40. edge dislocation
    • extra partial plane of atoms inserted in crystal structure
    • perpindicular to dislocation line
  41. screw dislocation
    • spiral planar ramp
    • due to shear deformation
    • parallel to dislocation line
  42. single crystal
    material with no grain boundries
  43. polycrystal
    • multiple crystal structures in material
    • multiple grain boundries
  44. grain boundry properties
    • high diffusion
    • high mobility
    • high chemical reactivity
  45. cold mount
    • cheap
    • can see sample
    • take a supstaintial amount of time to harden
  46. hot mounting
    • expensive
    • very fast
  47. hardness
    • materials resistance to plastic deformation
    • intrinsic property
  48. solute and solvent roles
    • solute dissolved into solvent
    • solvent is larger quantity

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