Lecture 6

Question 1

Extrinsic

Answer 1

Strength
Hardness
Toughness
Ductility 
Electrical Conductivity 
Thermal Conductivity
Corrosion resistance
Oxidation resistance

Question 2

Intrinsic

Answer 2

Specific heat capacity
Density
Modulus

Question 3

Macrostructure

Answer 3

Features that can be observed macroscopically

• Grain size in cast metals
• Aggregate in concrete
• Pore sizes in foams

Question 4

Microstructure

Answer 4

Features that can be observed microscopically

>1 μm for optical microscopy

Question 5

What can an engineer influence

Answer 5

Electronic structure- never
Crystal structure- occasionally
Microstructure- usually
Macrostructure-invariably

Question 6

Primary bonding

Answer 6

Electrons are shared or transfered

• Ionic
• Covalent
• Metallic

Question 7

Secondary

Answer 7

Attraction between electric dipoles

• Dipoles-dipole
• Hydrogen bonding

Question 8

Primary

Answer 8

Ionic- electron transfer (the ionic bond is not directional)
Covalent- electron sharing between two atoms
Metallic- electron sharing between any atoms

Question 9

Ionic bond

Answer 9

Only a few elements can accept electrons without an exorbitant energy penalty