COST 507 - Repositório Aberto da Universidade do Porto

The enthalpy of mixing of liquid Al-Cu-Li alloys were obtained for two sections with
constant composition ratios (Alo.8oLio.2o-Cu, Alo.^Cuo.ie-Li) at 945 K and 986 K,
respectively.
The enthalpy of formation of the congruently melting ternary phases T 5 -Fe2Al 7 4 Si and
T6-Fe 2 Al9SÌ2 was measured using an isoperibolic high temperature solution calorimeter
by solution in a liquid aluminium bath at 1343 K. The values for the enthalpies of
formation at 298 K are Af orm H(Fe2Al7. 4 Si) = -34.3 ± 2 kJ mol" 1 and A form H(Fe 2 Al 9 Si) =
-24.5±2kJmol" 1 .
The enthalpies of formation and fusion as well as the heat capacity of Mg 2 Si were
measured calorimetrically. The Al corner of the Al-Mg-Si ternary system was
investigated by DTA and optical micrography. A few points of the solvus of the
Al(fcc) solid solution were determined by dilatometry. The results of these
experiments together with literature data were used to redetermine a complete set of
analytical descriptions of the Gibbs energies of all stable phases of the Al-Mg-Si
system by (Dll).
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