Crystal Structure Flashcards
Fe
Iron, bcc to fcc (910)
Al
Aluminum, fcc
Ti
Titanium, hcp to bcc (882)
Cr
Cromium, bcc
Ni
Nickel, fcc
Cu
Copper, fcc
Zn
Zinc, hcp
Ag
Silver, fcc
Au
Gold, fcc
Pb
Lead, fcc
(hkl)
specific plane
family of directions
{hkl}
family of planes
[uvw]
specific direction
FCC stacking sequence is…
ABC…
HCP stacking sequence is…
ABAB…
Name 4 point defects (0‐dimensional)…
vacancies, self interstitial, interstitial, substitutional interstitial.
Name 3 line defects (1‐dimensional)…
edge dislocation, dislocation loop (interstitial type), dislocation loop (vacancy type)
Name 5 are (plane) defects (2‐dimensional)…
interfaces (stacking faults, surfaces, grain‐, phase‐, twin‐boundaries)
Name 4 volume (bulk) defects (3‐dimensional)…
pores/voids , precipitations, inclusions, cracks
Name 4 common that form interstitial solid solutions
B,C,N,O (because d/D
The 4 Hume‐Rothery rules (all of which are necessary)
for complete solubility in the solid state.
- atomic size factor: less than 15%
- same crystal lattice
- electronegativity
- vacancies
The first two are the most important.
Burgers vector direction for simple cubic?
[100]
Burgers vector direction for bcc?
[111]
Burgers vector direction for fcc?
[110]
Two types of dislocations are?
screw and edge
Twinning is very unlikely in fcc or bcc?
bcc.
Difference between an incoherent and coherent twin boundary (plane)?
A coherent twin boundary has a mirror plane. They’re less mobile (b/c of low energy) than incoherent boundaries.
Could have boundary energy as little as 20-40 times lower
Threshold (in degrees) between high (HAB) and low (LAB) angle grain boundaries
15 degrees.
two types of grain boundaries are…
tilt and twist
coherent twin planes have low boundary energies which is good for what…?
increased conductivity (Really, decreased resistivity)
The degree of segregation of solute elements decreases or increases with boundary energy?
increases
CSL stands for?
Coincidence Site Lattice
Gibbs free energy for binaries simplifies to, degrees of freedom (F) = …
F = 3-P. where p is the number of phases
What are the two temperatures on a Cu-Ni binary phase diagram with complete solid solubility? (corresponding to 100% Cu and 100% Ni.
1085 C and 1453C (the melting temperatures of Copper and Nickel, respectively)
Vegards rule for lattice constants?
a_new = a_a(1-x) + a_b(x)
Difference between intermediate phases and inter-metallic compounds?
Inter-metallic compounds have narrow region (strict composition criteria) and are associated with high melting points.
P+F = C+N
Gibbs free energy rule (phases, deg. freedom, components, N=1 for constant pressure)
What is coring and what contributes to it?
inhomogeneous internal grain structure, caused during nucleation when the diffusion in the solid is slower than the diffusion of the liquid.
What happens when both diffusion of liquid and solid are slow?
solute atoms, which are rejected from the solid remain near the solidification front in the melt (temperature in front of the solidification front in the melt is lower than T_liq = constitutional supercooling (i.e. caused by compositional changes) -> dendrites form from protuberances into that region of the melt.
Most important eutectic phase transformation?
Austenite “y” to Ferrite+Cementite “a+FeC3”, known as pearlite (happens at 0.73% C)
Whats strongest, incoherent, coherent or semicoherent, phase boundaries?
semicoherent (because of more misfit dislocations). This is key for precipitation hardening past GP I phase (coherent) into GPII/theta’’ or theta’ (semi coherent). But stop aging before theta (incoherent).
Mg
Magnesium, hcp
Li
Lithium, bcc to hcp
Name 4 light weight metals
Mg, Li, Ti, Al
Whats generally stronger, artificial or natural aging?
naturally aged metals
Name the pure iron, steel, cast iron regions in terms of percent carbon
Pure Iron
Two criteria for plastic deformation
Must have (1) dislocations and they must be able to (2) move.
2 requirements for deformation
5+ slip systems, and that they are active (depends on deformation rate and temperature). Else, twinning can occur.
4 methods for hardening
Solid solution hardening, grain refinement, work hardening, and precipitation hardening.
Difference between recovery and recrystallization?
Recrystallization involves the rearranging or annihilation of high angle grain boundaries
Explain Frank Read, Hall-Petch, and Vegards rule
(dislocation multiplication, grain size, mixing)
