Metal Crystal Structures

Question 1

The material properties are the same in all directions

Answer 1

Isotropic

Question 2

The material properties are different in all directions

Answer 2

Anisotropic

Question 3

3 main Metal Crystal Structures

Answer 3

FCC, BCC, HCP

Question 4

How many atoms and what is the CN of a FCC structure?

Answer 4

4 total atoms, CN=12

Question 5

How many atoms and what is the CN of a BCC structure?

Answer 5

2 total atoms, CN=8

Question 6

What is a polymorph?

Answer 6

more than one crystal structure

Question 7

What is an allotrope?

Answer 7

elemental solids (usually metals)

Question 8

When navigating crystal space, what is the notation for a) coordinates, b)directions, c)planes?

Answer 8

a) a b c
b) [u v w]
c) {h k l}

Question 9

What is the length of a FCC structure?

Answer 9

a=2R sqrt2

Question 10

What is the length of a BCC structure?

Answer 10

a= 4R sqrt3

Question 11

What are some polycrystalline characteristics

Answer 11

–Multiple small crystals = Grain (3D)
–Random crystallographic orientations
–grains grow and impinge

Question 12

Isotropic ___ vs. Anisotropic _____

Answer 12

same, different

Question 13

Theoretical density

Answer 13

p=nA/VN

Question 14

True or False: slipping occurs along loosely packed directions and planes

Answer 14

False. Slip occurs on densely packed directions and planes

Question 15

What is scattering?

Answer 15

By inputting light of the proper wavelength, we can use constructive/destructive interference of diffracted light to understand spacing

Question 16

Cleaving vs. fracturing?

Answer 16

cleaving: cleaves planes and directions. Occurs along planes of high planar density. common in anisotropic single crystals
Fracturing: Random crack and breakage points. Occurs in more isotropic materials.

Question 17

What is diffraction?

Answer 17

diffraction occurs when a wave encounters regularly spaced obstacles. They get constructive and destructive interference. Interference depends on wavelength and spacing and angle.