chapter 9: 상태도(phase diagrams)elearning.kocw.net/contents4/document/lec/2013/chosu… · ·...
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Chapter 9 - 1
ISSUES TO ADDRESS... • When we combine two elements...
what is the resulting equilibrium state?
• In particular, if we specify...
-- the composition (e.g., wt% Cu - wt% Ni), and
-- the temperature (T )
then...
How many phases form?
What is the composition of each phase?
What is the amount of each phase?
Chapter 9: 상태도(Phase Diagrams)
Phase B Phase A
Nickel atom Copper atom
Chapter 9 - 2
상평형(Phase Equilibria):
용해 한도(Solubility Limit)
Question: 20ºC 에서 물에 대한
설탕의 용해 한도는?
Answer: 65 wt% sugar. 20ºC, C < 65 wt% sugar: syrup
20ºC, C > 65 wt% sugar: syrup + sugar
65
• 용해 한도(Solubility Limit): 단상으로 구성하는 용매에
용해되는 용질의 최대 농도
Sugar/Water Phase Diagram
Su
gar
Tem
pera
ture
(ºC
)
0 20 40 60 80 100 C = Composition (wt% sugar)
L (liquid solution
i.e., syrup)
Solubility Limit L
(liquid)
+ S
(solid sugar) 20
4 0
6 0
8 0
10 0
Wate
r
Adapted from Fig. 9.1,
Callister & Rethwisch 8e.
• 고용체 – 고체, 액체, 기체상의 단상으로 구성
• 혼합 – 한 상 이상으로 구성
Chapter 9 - 3
• 성분(components): 합금을 구성하는 순금속이나 화합물
(e.g., Al and Cu)
• 상(phases): 물리적·화학적 특성이 균일한 계의 균질한 부분
(e.g., a and b).
Aluminum-
Copper
Alloy
성분과 상(Components and Phases)
a (darker
phase)
b (lighter
phase)
Adapted from chapter-
opening photograph,
Chapter 9, Callister,
Materials Science &
Engineering: An
Introduction, 3e.
Chapter 9 - 4
70 80 100 60 40 20 0
Tem
pera
ture
(ºC
)
C = Composition (wt% sugar)
L ( liquid solution
i.e., syrup)
20
100
40
60
80
0
L (liquid)
+ S
(solid sugar)
온도와 조성의 영향
• 온도(T)의 변화 – 상의 변화: path A to B.
• 조성(C)의 변화 – 상의 변화: path B to D.
water-
sugar
system
Adapted from Fig. 9.1,
Callister & Rethwisch 8e.
D (100ºC,C = 90)
2 phases
B (100ºC,C = 70)
1 phase
A (20ºC,C = 70)
2 phases
Chapter 9 - 5
고용체의 기준(Criteria for Solid Solubility)
Crystal Structure
electroneg r (nm)
Ni FCC 1.9 0.1246
Cu FCC 1.8 0.1278
• 두 가지 모두 같은 결정구조(FCC), 유사한 전기 음성도와
원자 반경(W. Hume – Rothery rules)는 높은 상호 고용도를
예측할 수 있음
단순 계 (e.g., Ni-Cu solution)
• Ni와 Cu는 모든 조성에서 서로 완전한 용해도를 보임
Chapter 9 - 6
상태도(Phase Diagrams)
• T, C와 P에 따른 상(phase) 구분
• 본 강의에서: - 2원계(binary systems): 2가지 성분으로 구성
- 독립 변수: 온도(T)와 성분(C) (P = 1 atm, 대기압)
Phase
Diagram
for Cu-Ni
system
Adapted from Fig. 9.3(a), Callister &
Rethwisch 8e. (Fig. 9.3(a) is adapted from
Phase Diagrams of Binary Nickel Alloys,
P. Nash (Ed.), ASM International,
Materials Park, OH (1991).
• 2 phases: L (liquid)
a (FCC solid solution)
• 3가지 다른 상 영역: L L + a
a
wt% Ni 20 40 60 80 100 0 1000
1100
1200
1300
1400
1500
1600 T(ºC)
L (liquid)
a (FCC solid solution)
Chapter 9 - 7
Cu-Ni
phase
diagram
전율고용 2원계 상태도
(Isomorphous Binary Phase Diagram) • Phase diagram: Cu-Ni system.
• System is:
Adapted from Fig. 9.3(a), Callister &
Rethwisch 8e. (Fig. 9.3(a) is adapted from
Phase Diagrams of Binary Nickel Alloys,
P. Nash (Ed.), ASM International,
Materials Park, OH (1991).
-- 2원계(binary) i.e., 2가지 조성:
Cu와 Ni
-- 전율고용체(isomorphous) i.e., 두 성분이 액상과
고상에서 서로 완전한
용해도를 갖음; a phase
field extends from
0 to 100 wt% Ni. wt% Ni 20 40 60 80 100 0
1000
1100
1200
1300
1400
1500
1600 T(ºC)
L (liquid)
a (FCC solid solution)
Chapter 9 -
wt% Ni 20 40 60 80 100 0 1000
1100
1200
1300
1400
1500
1600 T(ºC)
L (liquid)
a
(FCC solid
solution)
Cu-Ni
phase
diagram
8
Phase Diagrams: 상의 종류 결정
• Rule 1: T 와 Co를 알면: -- 존재하는 상(phase(s))의 종류를 알 수 있다.
• Examples:
A(1100ºC, 60 wt% Ni): 1 phase: a
B (1250ºC, 35 wt% Ni): 2 phases: L + a
B (
1250ºC
,35)
A(1100ºC,60) Adapted from Fig. 9.3(a), Callister &
Rethwisch 8e. (Fig. 9.3(a) is adapted from
Phase Diagrams of Binary Nickel Alloys,
P. Nash (Ed.), ASM International,
Materials Park, OH (1991).
Chapter 9 - 9
wt% Ni
20
1200
1300
T(ºC)
L (liquid)
a (solid)
30 40 50
Cu-Ni
system
Phase Diagrams:
상의 조성 결정 • Rule 2: T 와 Co를 알면 : --개개 상의 조성을 알 수 있다.
• Examples: TA
A
35 C0
32 CL
TA = 1320ºC:
액상(L) 만이 존재 CL = C0
( = 35 wt% Ni)
TB = 1250ºC:
두상 a 와 L 이 존재 CL = C liquidus ( = 32 wt% Ni)
Ca = C solidus ( = 43 wt% Ni)
TD = 1190ºC:
고상(a) 만이 존재 Ca = C0 ( = 35 wt% Ni)
C0 = 35 wt% Ni의 조성
D TD
tie line
4 Ca
3
Adapted from Fig. 9.3(a), Callister &
Rethwisch 8e. (Fig. 9.3(a) is adapted from
Phase Diagrams of Binary Nickel Alloys, P.
Nash (Ed.), ASM International, Materials
Park, OH (1991).
B TB
Chapter 9 - 10
• Rule 3: T 와 Co를 알면 : -- 개개 상의 무게 분율를 알 수 있다.
• Examples:
TA : 액상(L) 만이 존재
WL = 1.00, Wa = 0
TD : 고상( a ) 만이 존재
WL = 0, W a = 1.00
Phase Diagrams:
상의 무게 분율(양) 결정
wt% Ni
20
1200
1300
T(ºC)
L (liquid)
a (solid)
3 0 4 0 5 0
Cu-Ni
system
TA A
35 C0
32 CL
B TB
D TD
tie line
4 Ca
3
R S
TB : 두가지 a 와 L 존재
73.03243
3543
= 0.27
WL S
R + S
Wa R
R + S
C0 = 35 wt% Ni
Adapted from Fig. 9.3(a), Callister &
Rethwisch 8e. (Fig. 9.3(a) is adapted from
Phase Diagrams of Binary Nickel Alloys, P.
Nash (Ed.), ASM International, Materials
Park, OH (1991).
Chapter 9 - 11
• 공액선(Tie line) – 평형상태에서 2상 구역 내 각 상의
경계선과 연결 – 등온선(isotherm)
지렛대 원리(The Lever Rule)
각 상의 분율은?
공액선(tie line)을 지렛대로 간주(lever)
(teeter-totter 혹은 see-saw)
Ma ML
R S
Ma x S ML x R
L
L
LL
LL
CC
CC
SR
RW
CC
CC
SR
S
MM
MW
a
a
a
a
a
00
wt% Ni
20
1200
1300
T(ºC)
L (liquid)
a (solid)
3 0 4 0 5 0
B T B
tie line
C0 CL Ca
S R
Adapted from Fig. 9.3(b),
Callister & Rethwisch 8e.
Chapter 9 - 12
wt% Ni 20
120 0
130 0
3 0 4 0 5 0 110 0
L (liquid)
a
(solid)
T(ºC)
A
35 C0
L: 35wt%Ni
Cu-Ni
system
• 상태도: Cu-Ni system.
Adapted from Fig. 9.4,
Callister & Rethwisch 8e.
• C0 = 35 wt% Ni
alloy의 냉각에
따르는 미세조직의 변화
Ex: Cu-Ni Alloy의 냉각
46 35
43 32
a: 43 wt% Ni
L: 32 wt% Ni
B a: 46 wt% Ni L: 35 wt% Ni
C
E L: 24 wt% Ni
a: 36 wt% Ni
24 36 D
Chapter 9 -
• 느린 냉각속도: 평형 조직
• 빠른 냉각 속도: 유핵 조직
First a to solidify: 46 wt% Ni
Last a to solidify:
< 35 wt% Ni
13
• 냉각에 따른 Ca 의 조성 변화
• Cu-Ni의 경우: 최초 고상 a의 조성 Ca = 46 wt% Ni.
최종 고상 a 의 조성 Ca = 35 wt% Ni.
유핵 vs 평형 조직
(Cored vs Equilibrium Structures)
Uniform Ca:
35 wt% Ni
Chapter 9 - 14
기계적 성질: Cu-Ni System
• 고용체 강화의 영향:
-- Tensile strength (TS) -- Ductility (%EL)
Adapted from Fig. 9.6(a),
Callister & Rethwisch 8e.
Te
nsile
Str
en
gth
(M
Pa
)
Composition, wt% Ni Cu Ni 0 20 40 60 80 100
200
300
400
TS for pure Ni
TS for pure Cu
Elo
ng
atio
n (
%E
L)
Composition, wt% Ni Cu Ni 0 20 40 60 80 100
20
30
40
50
60
%EL for pure Ni
%EL for pure Cu
Adapted from Fig. 9.6(b),
Callister & Rethwisch 8e.
Chapter 9 - 15
2가지 조성 최소의 용해온도(T)를 갖는
특정 조성
Adapted from Fig. 9.7,
Callister & Rethwisch 8e.
2원 공정계
(Binary-Eutectic Systems)
• 3개의 단일상 구역
(L, a, b)
• 제한된 용해도:
a: 대부분 Cu
b: 대부분 Ag
• TE : TE 이하 액상 무
: 온도 TE 에서의
조성
• CE
Ex.: Cu-Ag system
Cu-Ag
system
L (liquid)
a L + a L + b b
a b
C , wt% Ag 20 40 60 80 100 0
200
1200 T(ºC)
400
600
800
1000
CE
TE 8.0 71.9 91.2 779ºC
Ag) wt%1.29( Ag) wt%.08( Ag) wt%9.71( baLcooling
heating
• 공정 반응(Eutectic reaction)
L(CE) a(CaE) + b(CbE)
Chapter 9 - 16
L + a L + b
a + b
200
T(ºC)
18.3
C, wt% Sn
20 60 80 100 0
300
100
L (liquid)
a 183ºC
61.9 97.8
b
• 150ºC 에서 40 wt% Sn-60 wt% Pb alloy: -- 존재하는 상 Pb-Sn
system
EX 1: Pb-Sn 공정계
Answer: a + b
-- 상의 조성
-- 각 상의 분율
150
40 C0
11 Ca
99 Cb
S R
Answer: Ca = 11 wt% Sn Cb = 99 wt% Sn
W a
= Cb - C0
Cb - Ca
= 99 - 40
99 - 11
= 59
88
= 0.67
S R+S
=
W b = C0 - Ca
Cb - Ca
= R
R+S
= 29
88
= 0.33 = 40 - 11
99 - 11
Answer:
Adapted from Fig. 9.8,
Callister & Rethwisch 8e.
Chapter 9 - 17
Answer: Ca = 17 wt% Sn
-- 상조성
L + b
a + b
200
T(ºC)
C, wt% Sn
20 60 80 100 0
300
100
L (liquid)
a b
L + a
183ºC
• 220ºC에서 40 wt% Sn-60 wt% Pb alloy: -- 존재 상: Pb-Sn
system
EX 2: Pb-Sn 공정계
-- 각 상의 분율
W a = CL - C0
CL - Ca
= 46 - 40
46 - 17
= 6
29
= 0.21
WL = C0 - Ca
CL - Ca
= 23
29
= 0.79
40 C0
46 CL
17 Ca
220 S R
Answer: a + L
CL = 46 wt% Sn
Answer:
Adapted from Fig. 9.8,
Callister & Rethwisch 8e.
Chapter 9 - 18
• C0 < 2 wt% Sn의 합금
• 결과: 상온 -- C0의 조성을 갖는 a phase
결정으로 구성된 다결정
공정계의 미세조직 I
0
L + a 200
T(ºC)
C , wt% Sn 10
2
20 C0
300
100
L
a
30
a + b
400
(room T solubility limit)
TE
(Pb-Sn System)
a L
L: C0 wt% Sn
a: C0 wt% Sn
Adapted from Fig. 9.11,
Callister & Rethwisch 8e.
Chapter 9 - 19
• 2 wt% Sn < C0 < 18.3 wt% Sn
합금
• 결과:
a + b 구역 내의 온도
-- a grains과 작은 b-phase
입자를 갖는 다결정
Adapted from Fig. 9.12,
Callister & Rethwisch 8e.
공정계의 미세조직 II
Pb-Sn
system
L + a
200
T(ºC)
C , wt% Sn 10
18.3
20 0 C0
300
100
L
a
30
a + b
400
(sol. limit at TE)
TE
2 (sol. limit at T room )
L
a
L: C0 wt% Sn
a b
a: C0 wt% Sn
Chapter 9 - 20
• 합금의 조성: C0 = CE
• 결과: 공정합금 미세조직, 층상 구조(lamellar structure)
-- a와 b 상의 층상(lamellae) 구조
Adapted from Fig. 9.13,
Callister & Rethwisch 8e.
공정합금의 미세조직 III
Adapted from Fig. 9.14,
Callister & Rethwisch 8e.
160 m
Micrograph of Pb-Sn eutectic microstructure
Pb-Sn
system
L b
a b
200
T(ºC)
C, wt% Sn
20 60 80 100 0
300
100
L
a b
L + a
183ºC
40
TE
18.3
a: 18.3 wt%Sn
97.8
b: 97.8 wt% Sn
CE 61.9
L: C0 wt% Sn
Chapter 9 - 21
Lamellar Eutectic Structure
Adapted from Figs. 9.14 & 9.15, Callister
& Rethwisch 8e.
Chapter 9 - 22
• 18.3 wt% Sn < C0 < 61.9 wt% Sn
• 결과: a상 입자와 공정형 미세구성인자
공정계의 미세조직 IV
18.3 61.9
S R
97.8
S R
primary a eutectic a
eutectic b
WL = (1- W a ) = 0.50
Ca = 18.3 wt% Sn
CL = 61.9 wt% Sn S
R + S Wa = = 0.50
• TE 직상 :
• TE 직하:
C a = 18.3 wt% Sn
C b = 97.8 wt% Sn S
R + S W a = = 0.73
W b = 0.27 Adapted from Fig. 9.16,
Callister & Rethwisch 8e.
Pb-Sn
system L +
b 200
T(ºC)
C, wt% Sn
20 60 80 100 0
300
100
L
a b
L + a
40
a + b
TE
L: C0 wt% Sn L a
L
a
Chapter 9 - 23
L + a L + b
a + b
200
C, wt% Sn 20 60 80 100 0
300
100
L
a b
TE
40
(Pb-Sn System)
아공석(Hypoeutectic) & 공석(Hypereutectic)
Adapted from Fig. 9.8,
Callister & Rethwisch 8e.
(Fig. 10.8 adapted from
Binary Phase Diagrams,
2nd ed., Vol. 3, T.B.
Massalski (Editor-in-Chief),
ASM International,
Materials Park, OH, 1990.)
160 m
eutectic micro-constituent Adapted from Fig. 9.14,
Callister & Rethwisch 8e.
hypereutectic: (illustration only)
b
b b
b b
b
Adapted from Fig. 9.17,
Callister & Rethwisch 8e.
(Illustration only)
(Figs. 9.14 and 9.17
from Metals
Handbook, 9th ed.,
Vol. 9,
Metallography and
Microstructures,
American Society for
Metals, Materials
Park, OH, 1985.)
175 m
a
a
a
a a
a
hypoeutectic: C0 = 50 wt% Sn
Adapted from
Fig. 9.17, Callister &
Rethwisch 8e.
T(ºC)
61.9
eutectic
eutectic: C0 = 61.9 wt% Sn
Chapter 9 - 24
금속간 화합물(Intermetallic Compounds)
Mg2Pb
Note: 금속간 화합물은 상태도에 선으로 표시- 면적이 아님 – 정해진
화학식을 갖음 (i.e. 화합물의 조성이 정해짐).
Adapted from
Fig. 9.20, Callister &
Rethwisch 8e.
Chapter 9 - 25
• Eutectoid – 1개의 고상이 2개의 다른 고상으로
상변화
S2 S1+S3
a + Fe3C (Fe-C의 경우, 727ºC, 0.76 wt%
C)
금속간 화합물 - cementite
cool
heat
공정(Eutectic), 공석(Eutectoid), &
포정(Peritectic) • Eutectic – 액상이 2개의 고상으로 상변화
L a + b (Pb-Sn의 경우, 183ºC, 61.9 wt% Sn)
cool
heat
cool
heat
• Peritectic – 액상과 고상이 다른 1개의 고상으로
상변화
S1 + L S2
+ L (Fe-C의 경우, 1493ºC, 0.16 wt% C)
Chapter 9 - 26
Eutectoid & Peritectic
Cu-Zn Phase diagram
Adapted from Fig. 9.21,
Callister & Rethwisch 8e.
Eutectoid transformation +
Peritectic transformation + L
Chapter 9 - 27
철-탄소 (Fe-C) 상태도
• 2 중요한 points
- Eutectoid (B):
a + Fe3C
- Eutectic (A):
L + Fe3C
Adapted from Fig. 9.24,
Callister & Rethwisch 8e.
Fe
3C
(ce
me
ntite
)
1600
1400
1200
1000
800
600
400 0 1 2 3 4 5 6 6.7
L
(austenite)
+L
+Fe3C
a +Fe3C
(Fe) C, wt% C
1148ºC
T(ºC)
a 727ºC = T eutectoid
4.30
Result: Pearlite = alternating layers of a and Fe3C phases
120 m
(Adapted from Fig. 9.27,
Callister & Rethwisch 8e.)
0.76
B
A L+Fe3C
Fe3C (cementite-hard)
a (ferrite-soft)
Chapter 9 - 28
Fe
3C
(ce
me
ntite
)
1600
1400
1200
1000
800
600
400 0 1 2 3 4 5 6 6.7
L
(austenite)
+L
+ Fe3C
a + Fe3C
L+Fe3C
(Fe) C, wt% C
1148ºC
T(ºC)
a 727ºC
(Fe-C
System)
C0
0.7
6
아공석 강(Hypoeutectoid Steel)
Adapted from Figs. 9.24
and 9.29,Callister &
Rethwisch 8e.
(Fig. 9.24 adapted from
Binary Alloy Phase
Diagrams, 2nd ed., Vol.
1, T.B. Massalski (Ed.-in-
Chief), ASM International,
Materials Park, OH,
1990.)
Adapted from Fig. 9.30, Callister & Rethwisch 8e.
proeutectoid ferrite pearlite
100 m Hypoeutectoid
steel
a
pearlite
a
a a
Chapter 9 - 29
Fe
3C
(ce
me
ntite
)
1600
1400
1200
1000
800
600
400 0 1 2 3 4 5 6 6.7
L
(austenite)
+L
+ Fe3C
a + Fe3C
L+Fe3C
(Fe) C, wt% C
1148ºC
T(ºC)
a 727ºC
(Fe-C
System)
C0
0.7
6
아공석 강(Hypoeutectoid Steel)
a
a a
s r Wa = s/(r + s)
W =(1 - Wa) R S
a
pearlite
Wpearlite = W
Wa’ = S/(R + S)
W =(1 – Wa’) Fe3C
Adapted from Figs. 9.24
and 9.29,Callister &
Rethwisch 8e.
(Fig. 9.24 adapted from
Binary Alloy Phase
Diagrams, 2nd ed., Vol.
1, T.B. Massalski (Ed.-in-
Chief), ASM International,
Materials Park, OH,
1990.)
Adapted from Fig. 9.30, Callister & Rethwisch 8e.
proeutectoid ferrite pearlite
100 m Hypoeutectoid
steel
Chapter 9 - 30
과공석 강(Hypereutectoid Steel)
Fe
3C
(ce
me
ntite
)
1600
1400
1200
1000
800
600
400 0 1 2 3 4 5 6 6.7
L
(austenite)
+L
+Fe3C
a +Fe3C
L+Fe3C
(Fe) C, wt%C
1148ºC
T(ºC)
a
Adapted from Figs. 9.24
and 9.32,Callister &
Rethwisch 8e. (Fig. 9.24
adapted from Binary Alloy
Phase Diagrams, 2nd
ed., Vol. 1, T.B. Massalski
(Ed.-in-Chief), ASM
International, Materials
Park, OH, 1990.)
(Fe-C
System)
0.7
6
C0
Fe3C
Adapted from Fig. 9.33, Callister & Rethwisch 8e.
proeutectoid Fe3C
60 m Hypereutectoid steel
pearlite
pearlite
Chapter 9 - 31
Fe
3C
(ce
me
ntite
)
1600
1400
1200
1000
800
600
400 0 1 2 3 4 5 6 6.7
L
(austenite)
+L
+Fe3C
a +Fe3C
L+Fe3C
(Fe) C, wt%C
1148ºC
T(ºC)
a
과공석 강(Hypereutectoid Steel)
(Fe-C
System)
0.7
6
C0
pearlite
Fe3C
x v
V X
Wpearlite = W
Wa = X/(V + X)
W =(1 - Wa) Fe3C’
W =(1-W)
W =x/(v + x)
Fe3C
Adapted from Fig. 9.33, Callister & Rethwisch 8e.
proeutectoid Fe3C
60 m Hypereutectoid steel
pearlite
Adapted from Figs. 9.24
and 9.32,Callister &
Rethwisch 8e. (Fig. 9.24
adapted from Binary Alloy
Phase Diagrams, 2nd
ed., Vol. 1, T.B. Massalski
(Ed.-in-Chief), ASM
International, Materials
Park, OH, 1990.)
Chapter 9 - 32
예제
99.6 wt% Fe-0.40 wt% C 강에 대하여 공석점
직하의 온도에서 다음을 결정하라:
a) Fe3C와 ferrite (a) 의 조성
b) 100 g의 강 중 cementite (in grams)의 양
c) 100 g 중 pearlite와 proeutectoid ferrite (a)의
양
Chapter 9 - 33
Solution to Example Problem
WFe3C R
R S
C0 Ca
CFe3C Ca
0.40 0.022
6.70 0.022 0.057
b) tie line에서 지렛대 원리 이용
a) 공석점 직하에서 RS tie line을 이용
Ca = 0.022 wt% C
CFe3C = 6.70 wt% C
Fe
3C
(ce
me
ntite
)
1600
1400
1200
1000
800
600
400 0 1 2 3 4 5 6 6.7
L
(austenite)
+L
+ Fe3C
a + Fe3C
L+Fe3C
C , wt% C
1148ºC
T(ºC)
727ºC
C0
R S
CFe C 3
Ca
100 g 중 Fe3C의 양
= (100 g)WFe3C
= (100 g)(0.057) = 5.7 g
Chapter 9 - 34
Solution to Example Problem (cont.)
c) 공석점 직상의 온도에서 VX tie line를 이용
C0 = 0.40 wt% C
Ca = 0.022 wt% C
Cpearlite = C = 0.76 wt% C
Fe
3C
(ce
me
ntite
)
1600
1400
1200
1000
800
600
400 0 1 2 3 4 5 6 6.7
L
(austenite)
+L
+ Fe3C
a + Fe3C
L+Fe3C
C, wt% C
1148ºC
T(ºC)
727ºC
C0
V X
C Ca
Wpearlite V
V X
C0 Ca
C Ca
0.40 0.022
0.76 0.022 0.512
100 g 중 pearlite의 양
= (100 g)Wpearlite
= (100 g)(0.512) = 51.2 g
Chapter 9 -
VMSE: Interactive Phase Diagrams
35 Change alloy composition
Microstructure, phase compositions, and phase fractions respond interactively
Chapter 9 - 36
Alloying with Other Elements
• Teutectoid changes:
Adapted from Fig. 9.34,Callister & Rethwisch 8e.
(Fig. 9.34 from Edgar C. Bain, Functions of the
Alloying Elements in Steel, American Society for
Metals, 1939, p. 127.)
T E
ute
cto
id (ºC
)
wt. % of alloying elements
Ti
Ni
Mo Si
W
Cr
Mn
• Ceutectoid changes:
Adapted from Fig. 9.35,Callister & Rethwisch 8e.
(Fig. 9.35 from Edgar C. Bain, Functions of the
Alloying Elements in Steel, American Society for
Metals, 1939, p. 127.)
wt. % of alloying elements
C e
ute
cto
id (w
t% C
)
Ni
Ti
Cr
Si Mn
W Mo
Chapter 9 - 37
• Phase diagrams are useful tools to determine:
-- the number and types of phases present,
-- the composition of each phase,
-- and the weight fraction of each phase
given the temperature and composition of the system.
• The microstructure of an alloy depends on
-- its composition, and
-- whether or not cooling rate allows for maintenance of
equilibrium.
• Important phase diagram phase transformations include
eutectic, eutectoid, and peritectic.
Summary
Chapter 9 - 38
Core Problems:
Self-help Problems:
ANNOUNCEMENTS
Reading: