MSEN 201 Final

Question 1

3 types of primary atomic bonding and if they’re directional

Answer 1

Ionic - non-directional
Covalent - directional
Metallic - non-directional

Question 2

dimensionality of:
- point defects
- line defects
- interfacial defects
- bulk defects

Answer 2

• point defects : 0D, ex: vacancy
• line defects: 1D, ex: dislocation
• interfacial defects: 2D, ex: grain boundary
• bulk defects: 3D, inclusions

Question 3

Hume-Rothery Rules

Answer 3

~determines solubility, all have to be simultaneously obeyed for complete solid solubility~

1. Atomic radii within 15% of each other
2. They need to have the same crystal structure
3. EN must be similar (difference in EN less than or equal to 0.4)
4. valence electrons similar (a metal is more likely to dissolve another metal of higher valency than one of lower)

Question 4

Cubic Crystal Structure

Answer 4

a=b=c
all 90 degrees

Question 5

tetragonal crystal structure

Answer 5

a=b ≠ c
all 90 degrees

Question 6

monoclinic crystal structure

Answer 6

a ≠ b ≠ c
α = γ = 90 , ≠ β

Question 7

orthorhombic crystal structure

Answer 7

a ≠ b ≠ c
all 90 degrees

Question 8

triclinic crystal structure

Answer 8

a ≠ b ≠ c
α ≠ β ≠ γ ≠ 90

Question 9

hexagonal crystal structure

Answer 9

a = b ≠ c
α = β =90, γ = 120

Question 10

Rhombohedral (trigonal) crystal structure

Answer 10

a = b = c
α = β = γ ≠ 90
–> all angles either 60 or 120

Question 11

dimension of mixed dislocation

Answer 11

1D

Question 12

dimension of a substitutional impurity atom

Answer 12

0D

Question 13

dimension of a grain boundary

Answer 13

2D

Question 14

dimension of a free surface

Answer 14

2D

Question 15

dimension of an inclusion

Answer 15

3D

Question 16

Fick’s 1st Law

Answer 16

J = -D (dc/dx)

J = diffusional flux
D = diffusivity
dc/dx = concentration gradient