This slide set corresponds to the MaterialsConcepts YouTube video "Muddiest Point- Phase Diagrams II: Eutectic Microstructures". Here is the link: http://www.youtube.com/watch?v=AbXIiN8iAeU To study the vocab used in this video, visit this site: http://quizlet.com/20699445/52-eutectic-pb-sn-phase-diagram-and-microstructures-flash-cards/ This work was supported by NSF Grants #0836041 and #1226325.

1. Muddiest
Points
Phase
Diagrams
II:
Eutec6c
Microstructures
Muddiest
Points:
•
How
do
I
determine
what
microstructure
looks
like?
• How
does
size
of
area
in
the
microstructure
diagram
relate
to
its
phase
frac6on?
•
“When
is
the
microstructure
alterna6ng
platelets
of
alpha
and
beta
vs.
blobs
of
alpha
or
beta?
• “Why
is
maximum
strength
at
the
eutec6c
composi6on?

2. Pb-Sn Phase Diagram: Effect of Composition on Strength
40
Strength
(Mpa)
30
20
10
327 o
300
232 o
200
183o
o 61.9 97.5
T, C 19.2
100
0
0%Sn 20%Sn 40%Sn 60%Sn 80%Sn 100%Sn
100%Pb 0%Pb
Composition, wt%

3. Single-­‐Phase
Region
Microstructures
Eutectic Phase Diagram Terminology
1.
T=
325°,
Co
=
10%
Sn
3.
T=
325°,
Co
=
99%
Sn
X
X
L !" L
α
!+!" .$'/010)2/301",)
Phases:
! # #"!"" Phases:
X
X
#
Chem.
5.$) Chem.
Comp:
Comp:
Phase
wt.
Phase
wt.
Fract.:
! + #"
Fract.:
!"#$%&#&'()#&*&') !"#$%&#&'()#&*&')
"+)!,)&,)!" "+)-%)&,)#"
2.
T=
182°,
Co
=
10%
Sn
) ) 4.
T=182°,
Co
=
99%
Sn
Co
Co
4.$)
56-+7827909"*+,-3" 56-7:7827909"*+,-3"
α
$%&'" *+,-+./0+)"$123"4"()'""" $()'" β
β
Phases:
Phases:
Chem.
Chem.
Comp:
Comp:
Phase
wt.
Phase
wt.
Fract.:
Fract.:

4. Eutec6c
Microstructure
TerminologySn
Eutectic Phase Diagram 61.9
wt.
%
L
!"
!+!" .$'/010)2/301",)
! X
# #"!""
1.
T=
184
°C,
Co=61.9%
Sn
5.$) X
#
R
S Phases:
Chem.
!"#$%&#&'()#&*&') ! + #" !"#$%&#&'()#&*&')
Comp:
"+)!,)&,)!" "+)-%)&,)#" Phase
wt.
) )
Fract.:
4.$)
56-+7827909"*+,-3" 56-7:7827909"*+,-3"
$%&'" *+,-+./0+)"$123"4"()'""" $()'" α
β
α 2.
T=
182°C,
Co=
61.9%
Sn
β Phases:
α Chem.
L
β
Comp:
EutecAc
α+
β
Wα=
S
Phase
wt.
Wβ= 1- Wα
α
Fract.:
R+S

5. Hypoeutec6c
Microstructure:
40
wt.
%
Sn
Terminology
Eutectic Phase Diagram
1.
T=
300
°C,
Co=
40
%
Sn
Phases:
X
Chem.
L !"
Comp:
Phase
T
U
17
!+!" .$'/010)2/301",)
X
46
wt.
Fract.:
2.
T=
225°C,
Co=
40
%
Sn
! C
X
D
# #"!""
X
#
Phases:
5.$)
α
L α
E
F
Chem.
Comp:
α
Phase
wt.
!"#$%&#&'()#&*&') ! + #" !"#$%&#&'()#&*&')
Fract.:
Wα=
U
WL= 1- Wα
"+)!,)&,)!" "+)-%)&,)#"
T+U
) )
α
L
α
Co
4.$)
3.
T=
184°C,
Co=
40
%
56-+7827909"*+,-3" 56-7:7827909"*+,-3"
α
Phases:
$%&'" *+,-+./0+)"$123"4"()'""" $()'"
Chem.
Comp:
Phases:
Phase
wt.
Wα=
D
WL= 1- Wα
Chem.
C+D
α
Comp:
Fract.:
α
Phase
wt.
F
α
Fract.:
Wα=
Wβ= 1 - Wα
4.
T=
182°C,
Co=
40
%
E+F

6. Hypereutec6c
Microstructure:
85
wt.
%
Sn
Eutectic Phase Diagram Terminology
1.
T=
300
°C,
Co=
85
%
Sn
Phases:
L Chem.
Comp:
X
Phase
wt.
Fract.:
!"
G
H
.$'/010)2/301",) β
+
L
2.
T=
210°C,
Co=
85
%
Sn
!
!+!" 80
J
X 98
Phases:
X #"!"" K
# Chem.
5.$) X
X
Y
# β
β
Comp:
Phase
wt.
β
L
Fract.:
Wβ=
G
!"#$%&#&'()#&*&') ! + #" !"#$%&#&'()#&*&') G+H
"+)!,)&,)!" "+)-%)&,)#"
WL= 1- Wβ
) )
L
β
4.$) Co
3.
T=
184°C,
Co=
85
%
Sn
56-+7827909"*+,-3" 56-7:7827909"*+,-3"
β
$%&'" *+,-+./0+)"$123"4"()'""" $()'" β
Phases:
Chem.
Comp:
Phases:
4.
T=
182°C,
Co=
85
%
Sn
Phase
wt.
Chem.
Wβ=
J
Fract.:
Comp:
J+K
β
Phase
wt.
WL= 1- Wβ
X
β
Fract.:
Wβ=
X+Y
Wα= 1 - Wβ
β
β
β

7. Summary
Phase Diagram icrostructures
Eutectic of
Eutec6c
M Terminology
!"
!+!" .$'/010)2/301",)
! # #"!""
α
5.$)
X
X
X
X
X
# β
β
T=
182°C,
Co
=
10%
Sn
!"#$%&#&'()#&*&') ! + #" !"#$%&#&'()#&*&') T=
182°C,
Co
=
99%
Sn
"+)!,)&,)!" "+)-%)&,)#"
) )
4.$)
56-+7827909"*+,-3" 56-7:7827909"*+,-3"
$%&'" *+,-+./0+)"$123"4"()'""" $()'"
α
β
α
β
α
β
T=
182°C,
Co
=
40%
Sn
T=
182°C,
Ceu
=
61.9
%
Sn
T=
182°C,
Co
=
85%
Sn

8. Pb-Sn Phase Diagram: Effect of Composition on Strength
40
Strength
(Mpa)
30
20
10
327 o
300
232 o
200
183o
o 61.9 97.5
T, C 19.2
100
0
0%Sn 20%Sn 40%Sn 60%Sn 80%Sn 100%Sn
100%Pb 0%Pb
Composition, wt%
α
β
α
β
α
β
Co
=
40%
Sn
Ceu
=
61.9
%
Sn
Co
=
85%
Sn

9. Quiz the Wiz- Eutectic Microstructures sec 9.12, pp. 305 – 309
Homework 12. Problem 5. Focused reading: Ch. 9,

10. Muddiest
Points
Phase
Diagrams
II:
Eutec6c
Microstructures
Muddiest
Points:
•
How
do
I
determine
what
microstructure
looks
like?
• How
does
size
of
area
in
the
microstructure
diagram
relate
to
its
phase
frac6on?
•
“When
is
the
microstructure
alterna6ng
platelets
of
alpha
and
beta
vs.
blobs
of
alpha
or
beta?
• “Why
is
maximum
strength
at
the
eutec6c
composi6on?