Euromet 2006 Influence of impurities on the melting temperature of Aluminum
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Transcript of Euromet 2006 Influence of impurities on the melting temperature of Aluminum
Euromet 2006
Influence of impurities on the melting temperature of Aluminum
Pr. B. Legendre & Dr S. Fries
EA 401
Impurities
• B, C, Cr, Cu, F, Fe, Mg, Mn, N, Ni, O, Pt
• S, Sc, Si, Ti, V, Zn.
• Al – X Optimized
• Al – Y Non optimized (or bad optimized), but the phase diagram is known
• Al – F no data
Aim
• Measurement of the slopes of the liquidus and of the solidus : = (dT/dx)
l : for the liquidus s : for the solidus
• The slope may be expressed in atomic fraction or in weight fraction.
• Determination of K :
• K = l/ s
• For Al Tfus= 660.323°C
Phase diagram
• For this subject we are interested only by a very small region in temperature and composition of binaries Al-X, but it is absolutely necessary to have a perfect knowledge of the full diagram. And to know the Gibbs function versus of T and x for each phase at a fixed pressure.
Phase diagram : Calphad Method
• A phase diagram is the graphical expression of phase equilibria, for each phase in a binary system G = f(xi, T, P)
• The limits of a two phase field are given by the common tangent of the G =f(xi)PT curves.
• For a eutectic:
• The three curves G=f(xi)p,T, have the same tangent.
•
The whole process
Cal
cula
tin
g p
has
e d
iag
ram
s
Al - Si
Al - Si
Al -Si
Al - B
Al - B
Al - B
Al - Pt
Al - Pt
Al - Pt
Al - Pt
Al - Cr
Al - Cr
Al - Ni
0
200
400
600
800
1000
1200
1400
1600
1800
TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MOLE_FRACTION NI
THERMO-CALC (2004.09.02:15.09) :AL NI DATABASE:USER
P=1E5, N=1.,FIXED PHASES: AL3NI5=0;
2004-09-02 15:09:12.97 output by user suzana from NBMICRESS
Al - Ni
Al - Fe
Al - Fe
Al - Fe
Al - Cu
Al - Cu
Al - Cu
Al - Sc
0
200
400
600
800
1000
1200
1400
1600
TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MOLE_FRACTION SC
THERMO-CALC (2004.09.01:15.01) :AL SC DATABASE:USER
2004-09-01 15:01:35.22 output by user suzana from NBMICRESS
Al - Sc
• No data for the solidus…
660.0
660.1
660.2
660.3
660.4
660.5
TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 1 2 3 4 5 6 7 8 9 1010-5
MOLE_FRACTION SC
THERMO-CALC (2004.09.02:18.55) :AL SC DATABASE:USER
P=1E5, N=1 FIXED PHASES: BCC_A2=0;
2004-09-02 18:55:39.18 output by user suzana from NBMICRESS
Al – O: not a good optimization
655
656
657
658
659
660
661
662
663
664
665
TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 1 2 3 4 5 6 7 8 9 1010-6
MOLE_FRACTION O
THERMO-CALC (2004.09.02:17.21) :AL O DATABASE:USER
P=1E5, N=1.;
3
3:X(FCC_A1,O),T-273.15
2004-09-02 17:21:42.10 output by user suzana from NBMICRESS
Al - O
• Why it is not possible to have a good optimization of the Al-O binary?
• The oxygen forms with Al an oxide which is a thin film fixed on the surface of Al and then it is a kind of protection (aluminum pans are used on the gas in a kitchen…) after the fixation of a first layer the oxygen cannot go deeper in Al. There is no homogeneity and no equilibrium.
Al - O
• L Al + Al2O3 T =~ 660°C
• Van’t Hoff law
• dln(aAl)/dT = H/RT2
• aAl ~ XAl
H = fusH(Al) = 10711.04J/mol
T = 0.452 K XAl= .9993316
• dT/dX = 676
Results
Comparison of results
Variation of the liquidus temperature versus of the
yield of impurities
• Tl = Tfus + i
• Tl = temperature of the liquidus
• Tfus temperature of fusion of pure Al
= dT/dx x : weight fractioni : yield of impurities in ppm*10-6
• Example : for Al-Cr i = 9.9*10-2ppm
= 466 Tl = 660.32°C
Temperature of liquidus and solidus for a yield of impurity
Conclusions
• It has been possible to determine the influence of impurities in Al for nearly all the selected elements.
• For O and S just an estimation has been possible.
• The most important modifications occurs with O and N
• It is possible to perform a calculation with two impurities.
Acknowledgement
• This work has been financially supported by LNE and BNM
• We are very grateful to these organisms for their contribution.
•
Al - Pt
400
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TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MOLE_FRACTION PT
THERMO-CALC (2004.09.02:14.46) :AL PT DATABASE:USER
P=1E5, N=1 FIXED PHASES: L12#2=0;
2004-09-02 14:46:40.29 output by user suzana from NBMICRESS
Al - Pt
Al - Pt
659.8
659.9
660.0
660.1
660.2
660.3
660.4
660.5
660.6
660.7
660.8
660.9
TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 1 2 3 4 5 6 7 8 9 1010-5
MOLE_FRACTION PT
THERMO-CALC (2004.09.02:19.20) :AL PT DATABASE:USER
P=1E5, N=1 FIXED PHASES: L12#2=0;
2004-09-02 19:20:17.48 output by user suzana from NBMICRESS
Al - Ni
659.95
660.00
660.05
660.10
660.15
660.20
660.25
660.30
660.35
660.40
TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 5 10 15 20 25 30 35 40 45 5010-5
MOLE_FRACTION NI
THERMO-CALC (2004.09.02:19.14) :AL NI DATABASE:USER
P=1E5, N=1.,FIXED PHASES: AL3NI5=0;
2004-09-02 19:14:42.95 output by user suzana from NBMICRESS
Al - Pt
656
657
658
659
660
661
662
663
664
665
666
TE
MP
ER
AT
UR
E_C
EL
SIU
S
0 1 2 3 4 5 6 7 8 9 1010-3
MOLE_FRACTION PT
THERMO-CALC (2004.09.02:14.50) :AL PT DATABASE:USER
P=1E5, N=1 FIXED PHASES: L12#2=0;
2004-09-02 14:50:03.08 output by user suzana from NBMICRESS
Applications of Gibbs energies descriptionscombined to kinetic Information
Creating Gibbs energies for each phase
Al - Si