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54 Cards in this Set
- Front
- Back
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Lattice Energy |
Energy to transfer one mole of ionic solid into gas state |
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lattice energy increases >> Tm ?
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increases |
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radius increases >> Tm? |
decreases |
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number of valence electrons increases >> Tm? |
increases |
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smaller distance between atoms >> lattice energy? |
decreases |
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FCC Face Centered Cubic coordination #? lattice parameter? |
coordination #: 12 lattice parameter: a=(4R/sqrt(2)) |
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BCC Body Centered Cubic coordination #? lattice parameter? |
coordination #: 8 lattice parameter: a=(4R/sqrt(3)) |
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Volume of a cell formula |
Vc=a^3 |
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Volume of the atoms of a cell formula |
Va = (4/3)*pi*R^3*(# of atoms in the cell) |
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Atomic packing factor formula |
APF = Va / Vc |
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HCP Hexagonal Close Packed coordination #? Base? Height? Volume? |
coordination #: 12 Base: B=6*R^2*sqrt(3) Height: h=(4*R*sqrt(2))/sqrt(3) Volume: B*h |
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FCC Number of atoms? Number of tetrahedral sites? Number of octahedral sites? |
4 atoms 8 tetrahedral 4 octahedral |
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BCC Number of atoms? Number of tetrahedral sites? Number of octahedral sites? |
2 atoms 12 tetrahedral 6 octahedral |
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HCP Number of atoms? Number of tetrahedral sites? Number of octahedral sites? |
6 atoms 12 tetrahedral 6 octahedrral |
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CsCl Structure |
Cl in corners Cs in center |
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NaCl (rock salt structure) |
Cl in FCC Na in octahedral |
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ZnS structure |
S in FCC |
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Miller indicies |
reciprocal values of intersections of plane with axes |
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Brag's Law |
dhkl = a/sqrt(h^2+k^2+l^2) 2*dhkl*sin(theta) = n*lambda (for xray diffraction) |
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volumetric density |
pv = mass/volume |
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planar density |
pp = # atoms/area |
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linear density |
pl = # atoms/length |
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point defects def. |
localized disruptions |
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# vacancies eqn |
nv = Nexp(-deltaHv/(R*T)) R=constant, T= temp |
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Shottky |
Pair of vacancies ns = Nexp(-deltaHs/(R*T)) |
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Frankel |
migration of atom to interstitial nf = sqrt(N*Ni)exp(-deltaHf(R*T)) |
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Substitutional Solid Solutions |
Replace host atoms similar radii, structure, valence, electronegativities |
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Interstitial Solid Solutions |
atoms occupy interstitial sites Radii smaller in solute similar electronegativites |
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burger's vector (b) |
describes magnitude and direction of distortion |
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edge dislocation |
extra plane of atoms dislocation line: bottom edge of inserted plane b: perpendicular to dislocation line, parallel to movement |
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screw dislocation |
cutting through and skewing the crystal one atom spacing dislocation line: line of distortion b: parallel to dislocation line, perpendicular to movement |
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slip direction is parallel to....? |
maximum packing direction |
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grain boundary defects decrease size >> resistance? |
resistance increases (limits dislocation movement) |
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solidus line def. |
line between solid and other |
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liquidus line def. |
line between liquid and other |
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eutectic structure means? |
layers of each component |
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hypo eutectic/oid |
left of the eutectic/oid point |
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hyper eutectic/oid |
right of eutectic/oid point |
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Find phase amounts (compositions) lever rule |
(length from point to line of opposite phase/ total length) *100 |
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Cold working >> dislocations? |
increase |
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cold working >> grain boundary length? |
increases |
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cold working >> dislocation mobility? and therefore hardness? and ductility? |
- mobility decreases - so hardness increases - and ductility decreases |
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What is needed for diffusion? |
- vacancies or interstitial points - thermal energy higher than activation energy |
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Activation energy def. |
Energy needed to move an atom to a new vacancy or interstitial site |
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activation energy increases >> melting point? |
increases |
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high melting point >> diffusion rate? |
is low |
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increase temperature >> diffusion rate? |
increases |
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open crystalline structure >> diffusion rate? |
increases |
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increase number of defects >> diffusion rate? |
increases |
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Atoms tend to move to areas with (lower/higher) concentration? |
lower |
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Steady state diffusion means? |
concentration does not change with time dC/dt = 0 |
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Fick's Law (flux) |
J= -D* dC/dx J=# atoms through surface area D = diffusivity dC/dx = concentration gradient |
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Diffusivity |
D = D0* exp(E*d/RT) |
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For non-steady diffusion we use? |
dC/dt = d/dx (D*dC/dx) >> error function and interpolation 1 - (Cx-C0)/(Cs-C0) = erf(x/(2*sqrt(Dt)) solve for t |
