Crystal Structure

Question 1

Fe

Answer 1

Iron, bcc to fcc (910)

Question 2

Al

Answer 2

Aluminum, fcc

Question 3

Ti

Answer 3

Titanium, hcp to bcc (882)

Question 4

Cr

Answer 4

Cromium, bcc

Question 5

Ni

Answer 5

Nickel, fcc

Question 6

Cu

Answer 6

Copper, fcc

Question 7

Zn

Answer 7

Zinc, hcp

Question 8

Ag

Answer 8

Silver, fcc

Question 9

Au

Answer 9

Gold, fcc

Question 10

Pb

Answer 10

Lead, fcc

Question 11

(hkl)

Answer 11

specific plane

Answer 12

family of directions

Question 13

{hkl}

Answer 13

family of planes

Question 14

[uvw]

Answer 14

specific direction

Question 15

FCC stacking sequence is…

Answer 15

ABC…

Question 16

HCP stacking sequence is…

Answer 16

ABAB…

Question 17

Name 4 point defects (0‐dimensional)…

Answer 17

vacancies, self interstitial, interstitial, substitutional interstitial.

Question 18

Name 3 line defects (1‐dimensional)…

Answer 18

edge dislocation, dislocation loop (interstitial type), dislocation loop (vacancy type)

Question 19

Name 5 are (plane) defects (2‐dimensional)…

Answer 19

interfaces (stacking faults, surfaces, grain‐, phase‐, twin‐boundaries)

Question 20

Name 4 volume (bulk) defects (3‐dimensional)…

Answer 20

pores/voids , precipitations, inclusions, cracks

Question 21

Name 4 common that form interstitial solid solutions

Answer 21

B,C,N,O (because d/D

Question 22

The 4 Hume‐Rothery rules (all of which are necessary)

for complete solubility in the solid state.

Answer 22

1. atomic size factor: less than 15%
2. same crystal lattice
3. electronegativity
4. vacancies
   The first two are the most important.

Question 23

Burgers vector direction for simple cubic?

Answer 23

[100]

Question 24

Burgers vector direction for bcc?

Answer 24

[111]

Question 25

Burgers vector direction for fcc?

Answer 25

[110]

Question 26

Two types of dislocations are?

Answer 26

screw and edge

Question 27

Twinning is very unlikely in fcc or bcc?

Answer 27

bcc.

Question 28

Difference between an incoherent and coherent twin boundary (plane)?

Answer 28

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

Question 29

Threshold (in degrees) between high (HAB) and low (LAB) angle grain boundaries

Answer 29

15 degrees.

Question 30

two types of grain boundaries are...

Answer 30

tilt and twist

Question 31

coherent twin planes have low boundary energies which is good for what...?

Answer 31

increased conductivity (Really, decreased resistivity)

Question 32

The degree of segregation of solute elements decreases or increases with boundary energy?

Answer 32

increases

Question 33

CSL stands for?

Answer 33

Coincidence Site Lattice

Question 34

Gibbs free energy for binaries simplifies to, degrees of freedom (F) = ...

Answer 34

F = 3-P. where p is the number of phases

Question 35

What are the two temperatures on a Cu-Ni binary phase diagram with complete solid solubility? (corresponding to 100% Cu and 100% Ni.

Answer 35

1085 C and 1453C (the melting temperatures of Copper and Nickel, respectively)

Question 36

Vegards rule for lattice constants?

Answer 36

a_new = a_a(1-x) + a_b(x)

Question 37

Difference between intermediate phases and inter-metallic compounds?

Answer 37

Inter-metallic compounds have narrow region (strict composition criteria) and are associated with high melting points.

Question 38

P+F = C+N

Answer 38

Gibbs free energy rule (phases, deg. freedom, components, N=1 for constant pressure)

Question 39

What is coring and what contributes to it?

Answer 39

inhomogeneous internal grain structure, caused during nucleation when the diffusion in the solid is slower than the diffusion of the liquid.

Question 40

What happens when both diffusion of liquid and solid are slow?

Answer 40

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.

Question 41

Most important eutectic phase transformation?

Answer 41

Austenite "y" to Ferrite+Cementite "a+FeC3", known as pearlite (happens at 0.73% C)

Question 42

Whats strongest, incoherent, coherent or semicoherent, phase boundaries?

Answer 42

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).

Question 43

Mg

Answer 43

Magnesium, hcp

Question 44

Li

Answer 44

Lithium, bcc to hcp

Question 45

Name 4 light weight metals

Answer 45

Mg, Li, Ti, Al

Question 46

Whats generally stronger, artificial or natural aging?

Answer 46

naturally aged metals

Question 47

Name the pure iron, steel, cast iron regions in terms of percent carbon

Answer 47

Pure Iron

Question 48

Two criteria for plastic deformation

Answer 48

Must have (1) dislocations and they must be able to (2) move.

Question 49

2 requirements for deformation

Answer 49

5+ slip systems, and that they are active (depends on deformation rate and temperature). Else, twinning can occur.

Question 50

4 methods for hardening

Answer 50

Solid solution hardening, grain refinement, work hardening, and precipitation hardening.

Question 51

Difference between recovery and recrystallization?

Answer 51

Recrystallization involves the rearranging or annihilation of high angle grain boundaries

Question 52

Explain Frank Read, Hall-Petch, and Vegards rule

Answer 52

(dislocation multiplication, grain size, mixing)