Lecture 8

Question 1

A phase can be

Answer 1

Continuous or discontinuous / a pure substance or a solution

Question 2

What is a phase?

Answer 2

It is a homogeneous, physically distinct and mechanically separable portion of the material with a given chemical composition and structure.

Question 3

Can gases be multiple phases?

Answer 3

No, gases can only be one phase.

Question 4

What gives a cooling curve?

Answer 4

Constant composition at varying temperatures.

Question 5

What gives an isothermal scan?

Answer 5

Constant temperature at varying compositions.

Question 6

Phase diagrams give:

Answer 6

1. The phases present
2. The composition of each phase present
3. The amount of each phase present

Question 7

What are the four phases in the iron-carbon phase diagram?

Answer 7

1. Delta-ferrite
2. Austenite
3. Ferrite
4. Cementite (Fe3C)

Question 8

What is the structure of ferrite?

Answer 8

BCC (Brittle)

Question 9

What is the structure of austenite?

Answer 9

FCC (Ductile)

Question 10

What is the Curie point?

Answer 10

The transition from non-magnetic to magnetic around 770C in the iron-carbon phase diagram.

Question 11

What are the properties of cementite?

Answer 11

Hard and brittle.

Question 12

Hypoeuctoid steels are XXX while hypereutectoid steels are XXX.

Answer 12

Softer (ductile), Harder (brittle)

Question 13

What enhances the oxidation and corrosion resistance in cast irons?

Answer 13

High silicon content.