Phase diagram

Material science

© Su-Jin Kim, GNU

Phase Diagrams(상태도)

1

Professor Su-Jin Kim

Gyeongsang National University

Phase diagram

Material science

© Su-Jin Kim, GNU

OCW

Solids Liquids and Gases (kids)

https://youtu.be/dCcTSfa82yU

17. Intro to Phase Diagrams

https://youtu.be/MJoYwtX_zFA

18. Phase Diagrams: The Lever Rule

https://youtu.be/_UGVDKlquxo

(Texas A&M)

Phase diagram

Material science

© Su-Jin Kim, GNU

OCW

Fe-Fe3C Phase Diagram1

https://www.youtube.com/watch?v=IUMcbctDNtM

Fe-Fe3C Phase Diagram2

https://www.youtube.com/watch?v=WUy4qED9Fv4

Fe-Fe3C Phase Diagram3

https://www.youtube.com/watch?v=wZgpTHZSuNY

Phase diagram

Material science

© Su-Jin Kim, GNU

KOCW

11. 상태도http://www.kocw.net/home/cview.do?lid=18a806f68e3cbebc

http://www.kocw.net/home/cview.do?lid=44ea277862a107ca

http://www.kocw.net/home/cview.do?lid=6d6c6800c280f9cf

Phase diagram

Material science

© Su-Jin Kim, GNU

Contents

Pressure Temperature Diagram of Water

Cu-Ni Phase Diagram

Fe-Fe3C Phase Diagram

Al-AlCu2 Phase Diagram

Phase diagram

Material science

© Su-Jin Kim, GNU

Phases(상): physically and chemically distinct

material regions (s l v)

Pressure-Temperature Diagram (Water)

0 100

Temperature (ºC)

Pre

ssu

re (

atm

)

1

0.006

218

Solid Liquid Vapor

Critical

point

Triple point

Ice Water Steam

Phase diagram

Material science

© Su-Jin Kim, GNU

Copper Nickel alloy

Phase diagram

Material science

© Su-Jin Kim, GNU

Cu-Ni Phase Diagram

1000

1100

1200

1300

1400

1500

0 20 40 60 80 100

Composition (wt% Ni) (Ni)(Cu)

Tem

pe

ratu

re (

ºC)

Liquid, L

Solid, α

L+α

Time

Ni

Cu

Cu + Ni

Te

mp

.

1453

1085

Phase diagram

Material science

© Su-Jin Kim, GNU

Lever rule

Composition (조성)

L : 30 wt% Ni

α : 40 wt% Ni

Weight ratio (비율)

L = b/c

= (40-32)/(40-30)

= 80%

α = a/c

= (32-30)/(40-30)

= 20%1100

1200

1300

30 40 (wt% Ni)

(ºC)

Liquid, L

Solid, α

L+α

32

1230

a b

c

32

Phase diagram

Material science

© Su-Jin Kim, GNU

Non-Equilibrium Cooling

1100

1200

1300

20 40 (wt% Ni)

(ºC)

Liquid, L

Solid, α

L+α

40%

35%

Equilibrium(slow)

cooling(평형냉각)

Uniform 32% Ni

Non-Equilibrium

cooling(비평형각)

Cored structure inside

40%~outside 30% Ni

32

30%

Phase diagram

Material science

© Su-Jin Kim, GNU

Cu-Ni Mechanical properties

200

300

400

0 20 40 60 80 100

Composition (wt% Ni) (Ni)(Cu)

Str

ength

(M

Pa)

20

40

60

0 20 40 60 80 100

Composition (wt% Ni) (Ni)(Cu)

Elo

ngation (

%)

Phase diagram

Material science

© Su-Jin Kim, GNU

Fe-Fe3C Phase Diagram

Austenite, Ferrite, Cementite phase vs. Perlite microstructure

Hypoeutectoid<Eutectoid(0.76%C)<Hypereutectoid

Reading phase diagram and drawing microstructure given temperature

and composition

Phase diagram

Material science

© Su-Jin Kim, GNU

Iron-Cementite Alloy : Steel (탄소강)

Fe-Fe3C Phase Diagram

Liquid, L

Austenite, γ

Ferrite, α

Cementite, Fe3C

α+γ

α+Fe3C

γ+Fe3C

γ+L

0 1 2 3 4 5 6 6.7400

Composition (wt% C)

Tem

pera

ture

(ºC

)

600

800

1000

1200

1400

1600

Phase diagram

Material science

© Su-Jin Kim, GNU

Austenite, Ferrite, Cementite

Fe-Fe3C Phase Diagram

Liquid, L

Austenite, γ

Ferrite, α Cementite, Fe3C

α+γ

α+Fe3C

γ+Fe3C

γ+L

0 1 2 3 4 5 6 6.7400

Composition (wt% C)

Tem

pera

ture

(ºC

)

600

800

1000

1200

1400

1600

2.14

0.022

ductile

FCC

ductile

BCC

hard, brittle

fixed composition

orthorhombic crystal

(Fe) (Fe3C)

Phase diagram

Material science

© Su-Jin Kim, GNU

Eutectic(공정): liquid transforms to two solid phases

Eutectoid(공석): one solid phase transforms to two other

solid phases

Eutetoid

Liquid, L

Austenite, γ

Ferrite, α

Cementite, Fe3C

α+γ

α+Fe3C

γ+Fe3C

γ+L

0 1 2 3 4 5 6 6.7400

Composition (wt% C)

Tem

pera

ture

(ºC

)

600

800

1000

1200

1400

1600

2.14 4.3

0.022

Eutectic

Cast Iron Carbon Steel

0.76

Eutectoid

727 ºC

1147ºC

g g

gg

Pearlite: α Fe3C layers (lamellar

structure)

Phase diagram

Material science

© Su-Jin Kim, GNU

Hypoeutectoid(아공석): C<0.76wt%, Pearlite+Ferrite

Hypereutectoid(과공석): C>0.76wt%, Pearlite+Cementite

Increase C Strength & Hardness ↑, Ductility ↓

Hypo. Hypereutectoid

Austenite, γ

Ferrite, α

α+γ

α+Fe3C

γ+L

0 1 2400

Composition (wt% C)

Tem

pera

ture

(ºC

)

600

800

1000

1200

1400

0.022

0.76

HypereutectoidHypoeutectoid

γ+Fe3C

g g

gg

g

g g

gFerrite, αFe3Cementite

gg

g g

pearlitepearlite

(Fe)

Phase diagram

Material science

© Su-Jin Kim, GNU

Aluminum-Copper phase diagram

Phase diagram

Material science

© Su-Jin Kim, GNU

Aluminum-Copper Alloy: Duralumin (4.4%Cu 1.5%Mg 0.6%Mn)

Al-AlCu2 Phase Diagram

CuAl2, θ

Liquid, L

α α+θ

α+L

0 10 20 30 40 50300

Composition (wt% Cu)

Tem

pera

ture

(ºC

)

400

500

600

700

θ+L

(Al) (CuAl2)

Eutectic

Phase diagram

Material science

© Su-Jin Kim, GNU

Contents

Pressure Temperature Diagram of Water

Cu-Ni Phase Diagram

Fe-Fe3C Phase Diagram

Al-AlCu2 Phase Diagram