Issues To Address... : - When We Combine Two Elements... - in Particular, If We Specify... Then..
Issues To Address... : - When We Combine Two Elements... - in Particular, If We Specify... Then..
Issues To Address... : - When We Combine Two Elements... - in Particular, If We Specify... Then..
Metallic Systems
ISSUES TO ADDRESS...
In particular, if we specify...
--a composition (e.g., wt% Cu - wt% Ni), and
--a temperature (T )
then...
Phase B
Phase A
Nickel atom
Copper atom
Chapter 9 - 1
Solubility
Limit
80
60
40
(liquid solution
i.e., syrup)
20
0
Pure
Water
Temperature (C)
100
L
(liquid)
+
S
(solid
sugar)
20
40
6065 80
100
Co =Composition (wt% sugar)
Pure
Sugar
Solubility Limit:
Chapter 9 - 2
Phases:
The physically and chemically distinct material regions
that result (e.g., and ).
AluminumCopper
Alloy
(lighter
phase)
(darker
phase)
Adapted from
chapter-opening
photograph,
Chapter 9,
Callister 3e.
Chapter 9 - 3
watersugar
system
Adapted from
Fig. 9.1,
Callister 7e.
Temperature (C)
100
80
(liquid)
60
L
(liquid solution
40
i.e., syrup)
+
S
(solid
sugar)
A (20C,70)
20
0
2 phases
2 phases
20
40
60 70 80
100
Co =Composition (wt% sugar)
Chapter 9 - 4
Phase Equilibria
Simple solution system (e.g., Ni-Cu solution)
Crystal
Structure
electroneg
r (nm)
Ni
FCC
1.9
0.1246
Cu
FCC
1.8
0.1278
Phase Diagrams
Indicate phases as function of T, Co, and P.
For this course:
-binary systems: just 2 components.
-independent variables: T and Co (P = 1 atm is almost always used).
T(C)
Phase
Diagram
for Cu-Ni
system
2 phases:
1600
1500
L (liquid)
1400
us
d
i
u
liq + s
L lidu
so
1300
(FCC solid
solution)
1200
1100
1000
L (liquid)
(FCC solid solution)
20
40
60
80
3 phase fields:
L
L+
100
wt% Ni
Chapter 9 - 6
Phase Diagrams:
# and types of phases
Rule 1: If we know T and Co, then we know:
--the # and types of phases present.
A(1100C, 60):
1 phase:
B(1250C, 35):
2 phases: L +
1600
L (liquid)
1500
B (1250C,35)
Examples:
T(C)
1400
1300
1200
L (FCC solid
solution)
1100
1000
Cu-Ni
phase
diagram
us
d
i
u
liq
us
d
i
l
so
A(1100C,60)
0
20
40
60
80
100
wt% Ni
Chapter 9 - 7
Phase Diagrams:
composition of phases
Rule 2: If we know T and Co, then we know:
--the composition of each phase.
Examples:
T(C)
Cu-Ni
system
A
TA
Co = 35 wt% Ni
tie line dus
qu i
i
l
1300 L (liquid)
At T A = 1320C:
+
L s
Only Liquid (L)
B
lidu
T
o
s
B
CL = Co ( = 35 wt% Ni)
At T D = 1190C:
L+
(solid)
1200
D
Only Solid ( )
TD
C = Co ( = 35 wt% Ni)
20
3032 35 4043
50
At T B = 1250C:
CLCo
C wt% Ni
Both and L
Adapted from Fig. 9.3(b), Callister 7e.
9.3(b) is adapted from Phase Diagrams
CL = C liquidus ( = 32 wt% Ni here) (Fig.
of Binary Nickel Alloys, P. Nash (Ed.), ASM
C = C solidus ( = 43 wt% Ni here) International, Materials Park, OH, 1991.)
Chapter 9 - 8
Phase Diagrams:
weight fractions of phases
Rule 3: If we know T and Co, then we know:
Cu-Ni
system
Examples:
Co = 35 wt% Ni
At T A : Only Liquid (L)
W L = 100 wt%, W = 0
At T D: Only Solid ( )
W L = 0, W = 100 wt%
At T B : Both and L
WL
W
S 43 35 73 wt %
R + S 43 32
R
= 27 wt%
R +S
T(C)
TA
L (liquid)
1300
TB
L
1200
TD
20
B
R S
D
3032 35
CLCo
+
L
us
d
i
l
so
(solid)
40 43
50
C wt% Ni
L (liquid)
1200
20
+
L
TB
L
us
d
i
l
so
+
R
ML
(solid)
R
30C C
40 C
L o
wt% Ni
WL
50
C C0
ML
S
ML M R S C CL
M S M L R
C CL
R
0
R S C CL
Chapter 9 - 10
System is:
--binary
i.e., 2 components:
Cu and Ni.
T(C) L (liquid)
130 0
L: 35 wt% Ni
: 46 wt% Ni
i.e., complete
solubility of one
component in
another; phase
field extends from
0 to 100 wt% Ni.
Consider
Co = 35 wt%Ni.
A
32
--isomorphous
L: 35wt%Ni
35
B
C
46
43
24
120 0
L+
Cu-Ni
system
L+
L: 32 wt% Ni
36
: 43 wt% Ni
L: 24 wt% Ni
: 36 wt% Ni
(solid)
110 0
20
30
35
Co
40
50
wt% Ni
Chapter 9 - 11
First to solidify:
46 wt% Ni
Last to solidify:
< 35 wt% Ni
Uniform C :
35 wt% Ni
Chapter 9 - 12
400
TS for
pure Ni
300
TS for pure Cu
200
0 20 40 60 80 100
Cu
Ni
Composition, wt% Ni
--Peak as a function of Co
Elongation (%EL)
60
50
40
30
20
0 20
Cu
40
60
80 100
Ni
Composition, wt% Ni
--Min. as a function of Co
Chapter 9 - 13
Binary-Eutectic Systems
has a special composition
with a min. melting T.
2 components
Cu-Ag
system
T(C)
1200
400
CE : Min. melting TE
composition
200
Eutectic transition
L(CE)
(CE) + (CE)
20
40
60 CE 80
100
Co , wt% Ag
C - CO
S
=
W =
R+S
C - C
300
200
150
100
99 - 40
59
=
=
= 67 wt%
99 - 11
88
C - C
W = R = O
C - C
R+S
=
Pb-Sn
system
40 - 11
29
=
= 33 wt%
99 - 11
88
L (liquid)
L+
183C
18.3
61.9
L+
97.8
S
+
0 11 20
C
40
Co
60
80
C, wt% Sn
99100
C
Chapter 9 - 15
Pb-Sn
system
300
220
200
L (liquid)
L+
R
L+
S
183C
100
CO - C
23
=
WL =
= 79 wt%
CL - C
29
+
0
17 20
C
40 46 60
80
Co CL C, wt% Sn
Chapter 9 - 16
100
Microstructures
in Eutectic Systems: I
Co < 2 wt% Sn
Result:
--at extreme ends
--polycrystal of grains
i.e., only one solid phase.
T(C)
L: Co wt% Sn
400
L
300
200
(Pb-Sn
System)
: Co wt% Sn
TE
100
L+
0
Co
10
20
30
Co , wt% Sn
2
(room T solubility limit)
Chapter 9 - 17
Microstructures
in Eutectic Systems: II
L: Co wt% Sn
T(C)
300
L +
200
TE
: Co wt% Sn
100
+
0
10
20
Pb-Sn
system
30
Co
Co , wt%
2
limit at Troom )
18.3
(sol. limit at TE)
Sn
Chapter 9 - 18
Microstructures
in Eutectic Systems: III
Co = CE
Result: Eutectic microstructure (lamellar structure)
--alternating layers (lamellae) of and crystals.
T(C)
L: Co wt% Sn
300
Pb-Sn
system
200
L+
100
183C
TE
20
18.3
40
Micrograph of Pb-Sn
eutectic
microstructure
: 97.8 wt% Sn
: 18.3 wt%Sn
60
CE
61.9
80
160 m
Adapted from Fig. 9.14, Callister 7e.
100
97.8
C, wt% Sn
Chapter 9 - 19
Chapter 9 - 20
Microstructures
in Eutectic Systems: IV
18.3 wt% Sn < Co < 61.9 wt% Sn
Result: crystals and a eutectic microstructure
T(C)
L: Co wt% Sn
300
Pb-Sn
system
200
L+
R
TE
100
20
18.3
L+
60
61.9
C = 18.3 wt% Sn
CL = 61.9 wt% Sn
W = S = 50 wt%
R+S
WL = (1- W) = 50 wt%
Just below TE :
primary
eutectic
eutectic
40
Just above TE :
80
Co, wt% Sn
100
97.8
C = 18.3 wt% Sn
C = 97.8 wt% Sn
W = S = 73 wt%
R+S
W = 27 wt%
Chapter 9 - 21
T(C)
200
L+
+
100
20
40
hypoeutectic: Co = 50 wt% Sn
(Figs. 9.14 and 9.17
from Metals
Handbook, 9th ed.,
Vol. 9,
Metallography and
Microstructures,
American Society for
Metals, Materials
Park, OH, 1985.)
L+
TE
60
80
eutectic
61.9
Adapted from
Fig. 9.17, Callister 7e.
Co, wt% Sn
175 m
100
(Pb-Sn
System)
160 m
eutectic micro-constituent
Adapted from Fig. 9.14,
Callister 7e.
Intermetallic Compounds
Adapted from
Fig. 9.20, Callister 7e.
Mg2Pb
Note: intermetallic compound forms a line - not an area because stoichiometry (i.e. composition) is exact. Chapter 9 - 23
cool
heat
+ Fe3C
(727C)
cool
heat
(1493C)
Chapter 9 - 24
Eutectoid transition
Peritectic transition + L
Adapted from
Fig. 9.21, Callister 7e.
Chapter 9 - 25
L + Fe3C
-Eutectoid (B):
+ Fe3C
T(C)
1600
1400
1200
+L
(austenite)
1000
800
600
120 m
Result: Pearlite =
alternating layers of
and Fe3C phases
(Adapted from Fig. 9.27, Callister 7e.)
S
+Fe3C
727C = Teutectoid
400
0
(Fe)
S
1
0.76
L+Fe3C
C eutectoid
1148C
+Fe3C
4
Fe3C (cementite)
2 important
points
-Eutectic (A):
6.7
4.30
Co, wt% C
Fe3C (cementite-hard)
(ferrite-soft)
Chapter 9 - 26
Hypoeutectoid Steel
T(C)
1600
+L
1200
(austenite)
1000
800
+ Fe3C
r s
727C
RS
(Fe)
pearlite
L+Fe3C
1148C
+ Fe3C
1
C0
0.76
w pearlite = w
(Fe-C
System)
Fe3C (cementite)
1400
6.7
Co , wt% C
100 m Hypoeutectoid
steel
w =S/(R+S)
w Fe3C =(1-w )
pearlite
proeutectoid ferrite
Adapted from Fig. 9.30,Callister 7e.
Chapter 9 - 27
Hypereutectoid Steel
T(C)
1600
+L
1200
(austenite)
1000
800
R
600
400
0
(Fe)
pearlite
L+Fe3C
1148C
+Fe3C
0.76
Fe3C
(Fe-C
System)
s
S
1 Co
w pearlite = w
w =S/(R+S)
w Fe3C =(1-w )
+Fe3C
2
Fe3C (cementite)
1400
6.7
Co , wt%C
60 mHypereutectoid
steel
pearlite
proeutectoid Fe3C
Adapted from Fig. 9.33,Callister 7e.
Chapter 9 - 28
Chapter 9 - 29
CO = 0.40 wt% C
C = 0.022 wt% C
CFe C = 6.70 wt% C
3
1600
1200
0.4 0.022
x 100 5.7g
6.7 0.022
(austenite)
94.3 g
+ Fe3C
727C
S
+ Fe3C
600
400
0
L+Fe3C
1148C
1000
800
Fe3C 5.7 g
+L
Fe C (cementite)
Fe3C
Co C
1400
x100 T(C)
Fe3C CFe3 C C
C CO
Co , wt% C
6.7
CFe
3C
Chapter 9 - 30
1600
1400
T(C)
+L
Co C
+ Fe3C
800
pearlite = 51.2 g
proeutectoid = 48.8 g
727C
RS
600
400
0
L+Fe3C
1148C
+ Fe3C
1
C CO C
Co , wt% C
Chapter 9 - 31
Fe C (cementite)
Co = 0.40 wt% C
C = 0.022 wt% C
Cpearlite = C = 0.76 wt% C
6.7
Ti
Mo
Si
Cr
Mn
Ni
Ceutectoid changes:
Ceutectoid (wt%C)
T Eutectoid (C)
Teutectoid changes:
Ni
Cr
Si
Ti Mo
Mn
Chapter 9 - 32
Summary
Phase diagrams are useful tools to determine:
--the number and types of phases,
--the wt% of each phase,
--and the composition of each phase
Chapter 9 - 33
ANNOUNCEMENTS
Reading:
Core Problems:
Self-help Problems:
Chapter 9 - 34