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Phase diagram: information about phases as function of T, composition, and pressure ... Sucrose/Water Phase Diagram. Pure. Sugar. Temperature (°C).
Typology: Lecture notes
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Phase B Phase A
Nickel atom
Copper atom
Definitions and basic concepts
alloy is composed
uniform physical and chemical characteristics
at a minimum under some specified combination of
temperature, pressure, and composition.
multiple phases
composition, and pressure
65
Sucrose/Water Phase Diagram
Pure Sugar
Temperature (°C)
(^0 ) (^40 60 80 )
C o
=Composition (wt% sugar)
L
(liquid solution
i.e., syrup)
Solubility
Limit L
(liquid)
+
S
(solid
(^20) sugar)
4 0
6 0
8 0
10 0
Pure Water
Question: What is the
Answer: 65wt% sugar.
o
o
+ sugar.
e.g., if T = 100C, solubility
limit = 80wt% sugar.
o
Adapted from
Fig. 9.1,
Callister 7e.
D (100°C,90)
2 phases
B (100°C,70)
1 phase
path A to B.
A (20°C,70)
2 phases
o
L
( liquid solution
i.e., syrup)
20
100
40
60
80
0
L
(liquid)
S
(solid
sugar)
water-
sugar
system
, and P.
o
( P = 1 atm is almost always used).
Diagram
for Cu-Ni
system
Adapted from Fig. 9.3(a), Callister 7e.
(Fig. 9.3(a) is adapted from Phase
Diagrams of Binary Nickel Alloys , P. Nash
(Ed.), ASM International, Materials Park,
OH (1991).
L (liquid)
α (^) (FCC solid solution)
wt% Ni 0 20 40 60 80 100
1000
1100
1200
1300
1400
1500
1600
T (°C)
L (liquid)
α
(FCC solid
solution)
wt% Ni
20
1200
1300
L (liquid)
α
(solid)
30 40 50
Cu-Ni
system
--the composition of each phase.
o
At T A
Only Liquid ( L )
o
( = 35 wt% Ni)
At T B
Both α^ and L
liquidus
( = 32 wt% Ni here)
α
solidus
( = 43 wt% Ni here)
At T D
Only Solid ( α)
α
o
( = 35 wt% Ni)
o
= 35 wt% Ni
Adapted from Fig. 9.3(b), Callister 7e.
(Fig. 9.3(b) is adapted from Phase Diagrams
of Binary Nickel Alloys , P. Nash (Ed.), ASM
International, Materials Park, OH, 1991.)
tie line
α
each other - essentially an isotherm
How much of each phase?
Think of it as a lever (teeter-totter)
M L
M α
R S
wt% Ni
20
1200
1300
L (liquid)
α
(solid)
3 0 4 0 5 0
tie line
C
o
C L
C α
R S
Adapted from Fig. 9.3(b),
Callister 7e.
20
120 0
130 0
3 0 4 0 5 0
110 0
L : 35wt%Ni
Cu-Ni
system
i.e. , 2 components:
Cu and Ni.
i.e., complete
solubility of one
component in
another; α phase
field extends from
0 to 100 wt% Ni.
Adapted from Fig. 9.4,
Callister 7e.
o
46
35
43
32
α: 43 wt% Ni
L : 32 wt% Ni
L : 24 wt% Ni
α: 36 wt% Ni
α: 46 wt% Ni
L : 35 wt% Ni
24 36
E
2 components
has a special composition
with a min. melting T.
Adapted from Fig. 9.7,
Callister 7e.
- Eutectic transition
L ( C E
) α( C α E
) + β( C β E
)
E
Ex.: Cu-Ag system
Cu-Ag
system
L (liquid)
α L^ +^ α
α + β
C o
, wt% Ag
0 20 40 60 80 100
200
1200
T (°C)
400
600
800
1000
C E
T E 8.0 71.9 91.
779°C
Binary eutectic systems (Example)
salt on ice that is at a
temperature below 0
0 C
can cause the ice to
melt.
α + β
200
T (°C)
C , wt% Sn
20 60 80 100 0
300
100
L (liquid)
α
β
L +α
183 °C
Pb-Sn
system
Adapted from Fig. 9.8,
Callister 7e.
O
= 40 wt% Sn
α
L
O
L
α
= 21 wt%
O
α
L
α
= 79 wt%
40
C o
46
C L
17
C α
220
α
= 17 wt% Sn
L
= 46 wt% Sn
