Phase diagrams
Equilibrium diagrams (in termodinamic
equilibrium)
Non-equilibrium diagrams (in
termodinamic non-equilibrium, in case of
technological processes)
.
Binary, ternary systems.
Equilibrium diagrams of binary
alloys
Two-dimensional diagram
which shows the type and
quantity of the equilibrium
phases at any concentration
and temperature.
Possible number of binary
diagrams: (n=90) > 4000
Gustav Tamman → 8 basic
types
1
Cooling curves
dQ felvett = dQleadott = m ⋅ c ⋅ dT = −α ⋅ A0 ⋅ (T − T0 ) ⋅ dt
T = T0 + (TK - T0 )e
-
αA 0
mc
t
Newton - cooling curve:
Ahol: T0
TK
α
A0
m
c
environmental temperature
initial temperature
(before cooling)
heat transfer coefficient
cross section area
mass
specific heat
T0
A
T, c
m α
dQ
Cooling curves
2
Cooling curves
Measuring phase diagrams
3
Likvidus, solidus
Informations from the phase
diagrams
• types of equilibrium phases
• composition of equilibrium phases
• ratio of equilibrium phases (lever rule)
4
Types of equilibrium phases
Types of equilibrium phases
5
Concentrations of equilibrium
phases
Cszil
Cátl
Cfoly
Ratio of equilibrium phases (lever
rule)
(O-S)msol=(L-O)mliq
msol/mliq=d/c
6
Unlimited solubility
Unlimited solubility
7
Simple eutectic system
Eutectic transformation
8
Cooling curve of eutectic
transformation
Limited solubility
Solvus line
9
Cooling curves, 0%
Cooling curves, 10%
10
Cooling curves, 30%
Intermetallic compound
olv.
α+olv.
A+AmBn
olv.
olv.+
AmBn
olv.+
AmBn
B+AmBn
11
Peritectic system
Peritectic system
Main importance:
Fe-C system
α + liq. → β
liq.
12