Modeling Metallothermic Reduction of Aluminium-Scandium Alloys in FactSage 7.2

Frederic Brinkmann, Carolin Mazurek Melting Point of Aluminium-Scandium Alloys

1409.1 °C 1400 Liquid 1204.0 °C 1200

C 1033.3 °C ° 1000

in in 910.7 °C

800 796.4 °C Al3Sc + Liquid 600

Temperature 400

+ Laves_C15 + Sc

200 3

Al AlSc Laves_C15 + AlSc Al3Sc + FCC_A1 0 0 10 20 30 40 50 Scandium in wt.-% Calculations in FactSage 7.2

Example for 20 wt.-% Al-Sc alloy

Equilib-Mode • Database: FactPS, FTlite

One liquid phase at 1204.04 °C Modeling Aluminium-Scandium Alloys

Metal distribution in alloy 100%

80%

%

-

.

wt in in 60%

40%

omposition c

Alloy 20%

0% 2% 5% 10% 20% 50% Sc to (Al+Sc)

Ca Al Sc Calculations in FactSage 7.2

Calculation of the composition of various Al-Sc alloys by using ScF3, Al2O3 and Ca as feed material

Example here for 5 wt.-% Al-Sc alloy

Equilib-Mode • Database: FactPS, FToxid, FTsalt and FTlite • Results at 1400 °C and 1 atm • Varying the amount of feed material to get Al-Sc alloys with different Sc-quantities (always starting with 1 g of Al) Calculations in FactSage 7.2

Metal distribution in alloy %

- 100% .

wt 80% in in 60%

40% omposition c 20%

Alloy 0% 2% 5% 10% 20% 50% Sc to (Al+Sc) Ca Al Modeling of the Slag 5 System for 20 % Al-Sc Alloy: 1 g ScF3+ 3,33 g Al2O3 + 4,52 g Ca

T in °C Here are the slags 2000 from the alloys previously shown 1800

1600

1400

1200

1000

0.1 Modeling of the Slag Target System: 1 g ScF3+ 3.33 + 0.3∙x g Al2O3+ 0.7∙x g CaF2 + 4.52 g Ca x: Coefficient on line

Coefficient x = 10 T in °C shows best results 2000

1800 Liquidus temperatur of the slag: 1247.5 °C 1600 1400

1200

1000

0.1 Calculations in FactSage 7.2

Calculated systems:

Equilib-Mode • Databases also FactPS, FToxid, FTsalt and FTlite • Results at 1400 °C and 1 atm • Varying the amount of feed material to get 20 wt.-% Al-Sc alloy with different slags Calculations in FactSage 7.2

Slag to metal ratio

Feed material Coefficient of x = 10 shows best results • Melting temperatur of slag is 1247.54 °C ScF3 1 g • Alloy composition is nearly targeted value Al O 6.332 g with 19.8 wt.-% Sc in Al-Sc alloy (after 2 3 destillation step for Ca-removal) CaF2 7 g • Slag to metal ratio is high but acceptable Ca 4.52 g Calculations in FactSage 7.2 Sc in Ca/Al: Reaction/Equilib module

1. 2.

Equilib module • Calculate Sc activity in the Al- Reaction module rich corner of the ternary Al- Sc-Ca system with multiple • Derive equilibrium activity of Sc binary cuts in contact Al2O3 (most unstable substance in system) • Indicate the regions where Sc activity is below the derived • Threshold for maximum content threshold attainable in Al-Sc-Ca alloy