Element Groups (Families)
Alkali Earth
Alkaline Earth
Transition Metals
Rare Earth
Other Metals
Metalloids
Non-Metals
Halogens
Noble Gases
1
1
2
3
4
5
6
2
3
4
5
6
7
8
9
10
11
12 13 14 15 16 17 18
H
He
252.87
-268.6
Li
Be
B
C
N
O
F
Ne
1347
2970
2550
4827
-195.8
-183
188.14
-246.1
Na
Mg
Al
Si
P
S
Cl
Ar
552.9
1107
2467
2355
280
444.6
-34.6
-186
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
774
1484
2832
3287
3380
2672
1962
2750
2870
2732
2567
907
2403
2830
613
684.9
58.78
-153.4
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
688
1384
3337
4377
4927
4612
4877
3900
3727
2927
2212
765
2000
2270
1750
989.8
184
-108.1
Cs
Ba
*
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
678.4
1140
5400
5425
5660
5627
5027
4527
3827
2807
356.58
1457
1740
1560
962
337
-61.8
Fr
Ra
Rf
Db
Sg
Bh
Hs
Mt
Uu
n
Uu
u
Uu
b
677
1737
?
?
?
?
?
?
?
?
?
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
3469
3257
3127
3127
?
1900
1597
3233
3041
2562
2720
2510
1727
1466
3315
Ac
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
3200
4790
?
3818
3902
3235
2607
?
?
?
?
?
?
?
?
**
7
*
**
PHASE DIAGRAMS
• STUDY OF PHASE RELATIONSHIPS IMPORTANT IN KNOWING
PROPERTIES OF MATERIALS
• MAP OF TEMPERATURE, PRESSURE AND COMPOSITION BETWEEN
PHASES IN EQUILIBRIUM IN A SYSTEM
GIBBS PHASE RULE
P+F=C+2
Eg: states of matter- gas, liquid and solid – single phase
Liquid mixture- oil and water- 2 phases
In solid , several phases depending on crystal structure
• STUDY IMPORTANT IN ALLOYS
• ALLOY- SUBSTANCE COMPOSED OF 2 OR MORE CHEMICAL
ELEMENTS
• MAIN CONSTITUENT- BASE METAL
AND OTHERS ALLOYING ELEMENTS
FUSION
LINE
ALMOST
VERTICALVARIATION
IN
PRESSURE
–NO
EFFECT ON
M.P. OF ICE
Phase Rule
FUSION
P
r
e
s
s
u
r
e
WATER
ICE
76cm
B
30 cm
WATER
VAPOUR
T
A
0
Temperature o C
100
50
•
•
•
•
•
•
•
•
•
•
At ‘A’ , water vapour - 1 phase
At ‘B’ , water and water vapour co exist -2 phases
At ‘T’ , ice, water and water vapour exist – 3 phases
At ‘A’
1 + F = chemical compound H2O + 2
F = 2 …. BIVARIANT
At ‘B’
2+ F = 1 +2, F = 1… UNIVARIANT
At ‘T’
All three phases P = 3, 3 + F = 1 + 2; F = 0
INVARIANT
Equilibrium Diagram
Case 1:
Binary Alloy with COMPLETE SOLUBILITY IN BOTH
LIQUID AND SOLID PHASES in all compositions
Eg: Ag-Au Cu-Ni Ge-Si Al2O3-Cr2O3 Sb-Bi
Silver-Palladium Co-Ni Cu-Pt Fe-Pt Ni-Pt Ta-Ti
HUME ROTHERY’S RULE-
FICK’S LAWS OF DIFFUSION
FIRST LAW
SECOND LAW
Cooling Curves & Phase Diagram
Elements A and B in a Binary Alloy
Phase (Equilibrium) Diagram
Temperature, T (ºC)
Liquid
Liquidus curve
L+α

T1
Solidus curve
0
20
40
60
Composition, C (% wt of B)
80
100
LEVER RULE
• With Fulcrum at P, weights WA and WB at
the end of a lever, for equilibrium, the lever
rule states:
WA / WB = b/a
WA
WB
P
a
b
Liquid
P1
P
X
Y
Liquid + Solid
16
37
47.5
Solid
58
For P: SS/LS = (37-16)/(58-37)= 1/1
For P1: SS/LS = 31.5/ 10.5= 3/1
Liquid
P1
P
X
Y
Liquid + Solid
Solid
31.5/ 10.5= 3
16
37
47.5
58
= (37-16)/(58-37)
1453
1083
The structures shown are at NON EQUILIBRIUM CONDITIONS
There are Three variables, one of these can be chosen as independent
If fl and fs are the liquid and solid fractions,
Case 2: Binary Alloy with COMPLETE
SOLUBILITY IN LIQUID STATE in all
compositions,
but COMPLETELY INSOLUBLE IN THE SOLID
•
•
•
•
STATE
A very doubtful situation in practice, since
most solid metals appear to dissolve small
quantities of other metals
In Bismuth-Cadmium, mutal solid solubility is
negligible.
Bi- heavy, brittle- positioned near to non
metals in periodic table- Rhombic type
structure-covalent bond
Cadmium- HCP-
Bismuth- Cadmium Equilibrium Diagram
Te
40Cd/60Bi
When two metals show complete solubility in liquid
state, and complete insolubility in the solid state,they
do so by crystallising out as alternate layers of the two
pure metals.
This laminated structure termed as EUTECTIC
INVARIANT REACTION
Te (EUTECTIC Temperature)
40Cd/60Bi
When two metals show complete solubility in liquid
state, and complete insolubility in the solid state, they
do so by crystallising out as alternate layers of the two
pure metals.
This laminated structure termed as EUTECTIC
A: Molten homogeneous alloy – 1 phase
with 2 components, Bi and Cd
1+F = 2 +1 (only temperature is the
variable, not pressure) , F=2
•B: 2 + F = 2 + 1, F= 1
•C: 3 + F = 2 + 1, F=0
At E, solid Cadmium (40%) and solid Bismuth(60%)
co-exist EUTECTIC
Eutectic is considered as
an intimate mixture of two metals
Phase Rule applied, P+F = C+ 1
3 + F = 2 +1, F = 0
Cooling curve for Eutectic (similar to pure metal)
Temperature o C
Time
For compositions to left /right of Eutectic
HUME ROTHERY’S RULE
Gold- Silver, Copper- Nickel, Germanium- Silicon,
Antimony- Bismuth,
Aluminium Oxide- Chromium Oxide etc.
are examples
FICK’S LAWS OF DIFFUSION
Mass Flow Process by which atoms
(molecules) change their positions
relative to their neighbours in a given
phase under the influence of thermal
energy and gradient
:
FICK’S LAWS OF DIFFUSION
FIRST LAW
dn/dt = no. of moles of B atoms crossing per unit time
D= Diffusion coefficient
A= Planar area
dc/dx= concentration gradient
If J = flux flow / unit area per unit time,
SECOND LAW
If D is independent of concentration,
INVARIANT REACTIONS
Case 3: Two metals completely soluble in
all proportions in liquid state, but partially
soluble in solid state
•
•
•
•
•
•
•
Melting Point of Lead:3270C
Melting Point of Tin: 2320C
Eutectic Temperature: 1830C
Eutectic Composition: 62% Sn, 38%Pb
Max. solid solubility tin in lead at 1830C: 19.5% tin
Max. Solid solubility of lead in tin at 1830C: 2.6% lead
Eutectic of two solid solutions α and β (instead of two
metals) form
Melting Point of Tin (Pb) : 2320C
Melting Point of Lead (Sn) :3270C
Eutectic Temperature: 1830C
Eutectic Composition: 38%Pb, 62% Sn
Max. solid solubility tin in lead at 1830C: 19.5% tin
Max. Solid solubility of lead in tin at 1830C: 2.6% lead
Liquid solubility of salt in water &
partial solid solubility of one metal in another(
(similarity schematically represented)