Chapter 9

Question 1

What does solution mean?

Answer 1

Solid, liquid, or gas solutions, single phase

Question 2

What is a mixture?

Answer 2

More than one phase

Question 3

What is the solubility limit?

Answer 3

The maximum concentration for which only a single phase solution exists.

Question 4

What are components?

Answer 4

The elements or compounds which are present in the alloy

Question 5

What are phases?

Answer 5

The physically and chemically distinct material regions that form.

Question 6

What are some characteristics of binary phase diagrams?

Answer 6

• Just two components
• T,C,P are used (P often is 1 atm)
• Two phases
• Three phase fields
• Isomorphous (complete liquid and solid solubility)

Question 7

What is a liquidus line?

Answer 7

On a binary phase diagram, the line or boundary separating liquid and liquid + solid-phase regions.

Question 8

What is a solidus line?

Answer 8

On a binary phase diagram, the line or boundary separating solid and liquid + solid-phase regions.

Question 9

How is phase composition determined?

Answer 9

If single phase: Co = Cp
If two phases: CL = Cliquidus, Cα = Csolidus

Question 10

What is the lever rule?

Answer 10

A mathematical expression by which the relative phase amounts in a two-phase alloy at equilibrium may be computed.

Question 11

How is the weight fraction of the L (liquid) phase determined?

Answer 11

WL = (Cα - Co) / (Cα - CL)

Question 12

How is the weight fraction of the α (solid) phase determined?

Answer 12

Wα = (Co - CL) / (Cα - CL)

Question 13

What is a tie line (isotherm)?

Answer 13

A horizontal line that connects the phases in equilibrium with each other

Question 14

How does cooling affect structure?

Answer 14

Slow: equilibrium structure (composition is equal)
Fast: cored structure (composition is layered, highest composition in center/core)

Question 15

What is a binary-eutectic system?

Answer 15

It has two components and a special composition with a minimum melting point

Question 16

What is an eutectic structure?

Answer 16

It is a lamellar structure (alternating layers) of solid phases

Question 17

What is an intermetallic compound?

Answer 17

A compound of two metals that has a distinct chemical formula. On a phase diagram it appears as an intermediate phase that exists over a very narrow range of compositions.

Question 18

What does eutectic mean?

Answer 18

Liquid transforms into two solid phases

Question 19

What does eutectoid mean?

Answer 19

One solid phase transforms into two other solid phases

Question 20

What does peritectic mean?

Answer 20

Liquid and one solid phase transform to a second solid phase

Question 21

What is austenite?

Answer 21

Face-centered cubic iron; also iron and steel alloys that have the FCC crystal structure.

Question 22

What is cementite?

Answer 22

Iron carbide (Fe3C).

Question 23

What is ferrite?

Answer 23

Ceramic oxide materials composed of both divalent and trivalent cations (e.g., Fe2+ and Fe3+), some of which are ferrimagnetic.

Question 24

What is pearlite?

Answer 24

A two-phase microstructure found in some steels and cast irons; it results from the transformation of austenite of eutectoid composition and consists of alternating layers (or Lamellae) of Α-ferrite and cementite.

Question 25

What does hypoeutectoid mean?

Answer 25

Before the

Question 26

What does monotectic mean?

Answer 26

Liquid transforms into a second liquid phase and a solid phase

Question 27

What does peritectoid mean?

Answer 27

Two solid phases turn into a third solid phase

Question 28

What is a congruent transformation?

Answer 28

A transformation of one phase to another while maintaining the same composition.

Question 29

What does hypoeutectoid mean?

Answer 29

Before the eutectoid composition

Question 30

What does hypereutectoid mean?

Answer 30

After the eutectoid composition