mse 09 phase diagrams(39) 091116
TRANSCRIPT
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
1/39
Introduction to
.
1http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
2/39
Contents
1 IntroductionIntroduction
Solubility LimitSolubility Limit2
Phase DiagramsPhase Diagrams3
Microstructural Evolution durin CoolinMicrostructural Evolution durin Coolin4
2
--
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
3/39
Issues to address
en we com ne two e ements... What equilibrium state do we get?
In particu ar, i we speci y...
Composition (e.g., atomic % Ge atomic % Sn), andTemperature (T )
Then...
How many phases do we get? What is the composition of each phase?
How much of each phase do we get?
ase
3Nickel atomCopper atom
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
4/39
Phase: chemically and structurally homogeneous region of material.
Components: chemically distinct and essentially indivisible
substance.
Solubility limit - maximum concentration of solute that may
dissolve in a solvent at a given tem erature to form a solid solution.
Precipitate - a solid phase that forms from the original matrix
hase when the solubilit limit is exceeded.
Phase diagram - graphical representation of the phases present
and the ran es in com osition tem erature and ressure over
which the phases are stable.
: = +
C : # components
4
F : degree of freedom (temperature, pressure, composition.)http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
5/39
Binary phase diagram - A phase diagram for a system with two
componen s. Ternary phase diagram - A phase diagram for a system with three
.
Isomorphous phase diagram - A phase diagram in which components
display unlimited solid solubility.
Liquidus temperature - The temperature at which the first solidbegins to form during solidification.
Solidus temperature - The temperature below which all liquid hascompletely solidified.
-metals that has its own unique composition, structure, and
properties. Eutectic - A three-phase invariant reaction in which one liquid
phase solidifies to produce two solid phases.
5
Peritectic - A three-phase reaction in which a solid and a liquidcombine to produce a second solid on cooling.http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
6/39
Contents
1 IntroductionIntroduction
Solubility LimitSolubility Limit2
Phase DiagramsPhase Diagrams3
Microstructural Evolution durin CoolinMicrostructural Evolution durin Coolin4
6
--
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
7/39
Phases & Solubility
(a) The three forms of water
gas, iqui so i are
each a phase.
(b) Water and alcohol have
unlimited solubility.
(c) Salt and water have limited
solubility.
(d) Oil and water have virtually
7 no solubility.http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
8/39
Solubility Limit
-Liquid copper-nickel are
completely soluble.
- Solid copper-nickel are
com letel soluble, with
copper and nickel atoms
occupying random lattice
sites.
8
- In copper-zinc alloys containing more than 30 at. % Zn,
a second phase forms because of the limited solubility of zinc in copper.http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
9/39
Solubility Limit
Solubility limit - maximum concentration of solute that may dissolve in asolvent at a given temperature to form a solid solution.
Precipitate - a new solid phase that forms when the solubility limit is
exceeded.
(Fig. 9-1)
9http://bp.snu.ac.kr
C12H22O11 H2O
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
10/39
Solubility Limit
Phase Diagram of) Solubility
100
Water - Sugar System
ture(
L
Limit (liquid)
+60
80
emper
(liquid solutioni.e., syrup)
S(solidsu ar20
40
solubility limit at 20C?
ar
0 20 40 60 80 100
65 r
.
If Co < 65 wt. % sugar: syrupPur
Sug
Pur
Wat
o > wt. sugar: syrup + sugar
Solubilit limit increases with T :
10
e.g., if T= 100C, solubility limit = 80 wt. % sugarhttp://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
11/39
Components and Phases
om onenThe elements or compounds which are mixed initially
(e.g., Al and Cu).
Phases:The physically and chemically distinct material regions
that result.
Aluminum-Copper Alloy
1 component (H2O)
phase)
ar e
phase)
11http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
12/39
Contents
1 IntroductionIntroduction
Solubility LimitSolubility Limit2
Phase DiagramsPhase Diagrams3
Microstructural Evolution durin CoolinMicrostructural Evolution durin Coolin4
12
--
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
13/39
Fundamental Concepts
Phase diagram: graphical representation of the phases
resent and the ran es in com osition tem erature
and pressure over which the phases are stable. Gi s p ase ru e: F= + 2 P
C: # components, P: # phases in equilibrium
(Eq. 9-16)
F: degree of freedom (temperature, pressure, composition.)
ex 2 , = , = + = -
1 phase F= 2
2 phase F= 1
3 phase F= 0 (invariant)
13 * pressure constant F= C+ 1 Phttp://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
14/39
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
15/39
Isomorphous Phase Diagram
Complete liquid and solid solutions
Constant ressure:(Fig. 9-3)
15 F= C+ 1 P, C= 2, F= 3 - Phttp://bp.snu.ac.kr
- 2009-10-28
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
16/39
Phase Diagrams
Tell us about the phases as a function of T, Co, and P For this course:
- Binary systems: just 2 components
- Inde endent variables: Tand Co (at P= 1 atm)
1600
1400
1500T(C)
L (liquid)
Cu-Ni
(FCC solid solution)1300
1100
1200
(FCC solid
16 20 40 60 80 10001000
so u on
wt% Ni http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
17/39
Phase Diagrams: Number and Types of Phases
Rule 1: If we know Tand Co, then we know:- the number and t es of hases resent.
Examples:
1600
L li uid
Cu-Ni
,
1 phase:
1400
50,35)
,2 phases: L + 1300
(FCC solidB(1
1100 A(1100,60)
17 wt% Ni20 40 60 80 10001000http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
18/39
Phase Diagrams: Composition of Phases
Rule 2: If we know Tand Co, then we know:- the composition of each phase.
Examples: Cu-Ni systemT(C) (Fig. 9-3)
At TA:
Only Liquid (L)
o
130 0 L (liquid)
TA tie line
CL= Co( = 35wt% Ni)At TD:TB
B
At TB:
C= Co( = 35wt% Ni)
120 0
(solid)D Both and L
CL= Cliquidus( = 32wt% Ni here)
TD
18
= solidus = w ere
wt% NiC oC L Chttp://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
19/39
Phase Diagrams: Fractions of Phases
Rule 3: If we know Tand Co, then we know:- the amount of each phase (given in wt. or at. %).
Cu-Ni system Examples:
Co= 35wt%Ni
T(C)
A At TA: Only Liquid (L)
WL= 100wt%, W= 0
1300 L (liquid)B
e ne
At TB: Both and L
WL= 0, W= 100wt%
1200
DB R S
20 30 40 50443532CC C
What would be WL and W?
44 35S wt% Ni= =44 32
wL R + S
19
= =
25 %
44 32
wtW =R + S
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
20/39
The Lever Rule (Proof)
Sum of weight fractions:
WL + W = 1
=
(Example 9-1)
Combine above equations:
= R
R +SW =
Co CLC C
= S
R+ SWL
= CCo
C C
: CoCL C
W
L
R = W
S
WWL 1 W
20 solving gives Lever Rulehttp://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
21/39
Contents
1 IntroductionIntroduction
Solubility LimitSolubility Limit2
Phase DiagramsPhase Diagrams3
Microstructural Evolution durin CoolinMicrostructural Evolution durin Coolin4
21
--
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
22/39
Cooling in a Cu-Ni Binary (equilibrium)
Phase diagram: Cu-Ni system. System is:
(Fig. 9-4 incorrect)
- binary
2 components: Cu and Ni
- isomorphous
com lete solubilit
.
A phase field extendsFrom 0 to 100 wt. % Ni
.
ConsiderCo = 35 wt. % Ni
What would be the
22 microstructures?http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
23/39
Coolin in Cu-Ni(nonequilibrium) .
(skip)
F g. -5
ConsiderCo = 35 wt. % Ni. X
23http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
24/39
Contents
1 IntroductionIntroduction
Solubility LimitSolubility Limit2
Phase DiagramsPhase Diagrams3
Microstructural Evolution durin CoolinMicrostructural Evolution durin Coolin4
24
--
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
25/39
Binary Eutectic Systems
A special compositionwith an eas meltin T
Greek - Easily melting (Fig. 9-7)
2 components
utectic reactionL
____
25http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
26/39
Binary Eutectic Systems
2 components as a spec a compos onwith a minimum melting T.
Ex.: Cu-Ag system 1200
T(C) (Fig. 9-7)
(L,, )
Limited solubility: L + L+
1000
: mostly Cu: mostly Ag
600E
8.0 71.9 91.2
CE: Min. melting T +
400
20 40 60 80 1000 CE
Cu Composition (wt. %) Ag
26http://bp.snu.ac.kr
- 2009-11-02
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
27/39
Example: Pb-Sn Eutectic System
For a 40 wt. % Sn 60 wt. % Pb alloy at 150C, find...
- e a e re en
- the compositions of the phases:
(Fig. 9-8)
(Fig. 9-9) = wt. n
C = 99 wt. % Sn
T C
300
- the relative amountsof each phase: L + L+200
qu
=59
=
18.3 61.9 97.8150
R S 88
=29
=
+
27
88
http://bp.snu.ac.krPb Composition (wt. %) Sn
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
28/39
Microstructures in Eutectic Systems - I
Co < 2 wt. % Sn
T(C) L: Co wt. % Sn4 00
(Fig. 9-11)
esu
polycrystal of grains 3 00 L
L +
2 0 0 : C o wt%SnT E
- n
System)
1 00 +
1 0 2 00 3 0
28
C o , wt% Sn2
C o
(room T solubility limit) http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
29/39
Microstructures in Eutectic Systems - II
2 wt. % Sn < Co < 18.3 wt. % Sn
T C L: C o wt.% Sn(Fig. 9-12)
with fine crystals. L400
L
: C owt%SnL +
300
200
TE
1 00 + XX
Pb-Snsystem
C wt. % n1 0 200
C30
29 (solubility limit at TE)
(solubility limit at Troom
18.3.
)
http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
30/39
Microstructures in Eutectic Systems - III
o = E Result Eutectic microstructure --- alternating.
-(Fig. 9-13) (Fig. 9-14)T(C)
300L: Cowt%Sn
L + 200 L +183C
100 +160m
: 18.3wt%Sn
0
: 97.8wt%Sn
30 Co, wt% SnC
E18.3 97.8
61.9http://bp.snu.ac.kr
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
31/39
Formation of Eutectic Lamellar Structure
(Fig. 9-15)
31http://bp.snu.ac.kr
E
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
32/39
Microstructures in Eutectic Systems
18.3 wt. % Sn < Co < 61.9 wt. % Sn Result: crystals and an eutectic microstructure
Just above TE : L(Fig. 9-16)
C = 18.3 wt. % Sn
C L = 61.9 wt. % Sn300 L
L
WL = (1-Wa) =50 wt. %R + S
W
==50 wt. %L +
200 TEL + SR
-
system
Just below TE :C = 18.3 wt. % Sn
1 00
+ C = 97.8 wt. SnS
R + SW = =73 wt. %
20 400 600
80 100Co18.3 61.9
r mary
97.8
eutectic eutectic
32
W = 27 wt. %o, w . n
http://bp.snu.ac.kr
(Fig. 9-17)
I i R i
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
33/39
Invariant Reactions
___
____
33http://bp.snu.ac.kr
O h E l
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
34/39
Other Examples
Fi . 9-20
34http://bp.snu.ac.kr
O h E l
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
35/39
Other Examples
. -
35http://bp.snu.ac.kr
Other Examples
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
36/39
Other Examples
(Fig. 9-22)
36http://bp.snu.ac.kr
C t t
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
37/39
Contents
1 IntroductionIntroduction
Solubility LimitSolubility Limit2
Phase DiagramsPhase Diagrams3
Microstructural Evolution duringMicrostructural Evolution during4
oo ngoo ng
37
--
http://bp.snu.ac.kr
F C h s di m
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
38/39
Fe-C phase diagram
iron (Fig. 9-24)
(FCC)
A
iron Cementite Fe CB
err te(BCC)
soft & ductile
hard & brittle
A; eutectic
38
B; eutectoidconcen ra on . w . w . w
iron steel cast ironhttp://bp.snu.ac.kr
S
-
8/10/2019 MSE 09 Phase Diagrams(39) 091116
39/39
Summary
Phase diagrams are useful tools to determine: The number and types of phases.
The at. % or wt. % of each phase.
.
For the given Tand composition of the system.
Binary alloys allow various ranges of microstructures.
Problems from Chap. 9 http://bp.snu.ac.kr
. - . - . - . -
Prob. 9-9 Prob. 9-11 Prob. 9-12 Prob. 9-17
39
ro . - ro . - ro . - ro . -
http://bp.snu.ac.kr