Assessments of Sc-Containing Ternary Systems Al-Sc-Ti and Al-Sc-Zr Within the Thermodynamic Database for Aluminium Alloys, TCAL5

This paper presents the assessment of two Sc-containing ternary systems, Al-Sc-Ti and Al-Sc-Zr, within the project for developing the thermodynamic database for aluminium alloys TCAL5. A brief review was made on the Al-rich phase equilibria, which are relevant to the (Al) matrix phase and the hardening precipitate Al3Sc. The assessment highlights the modeling of molar volume of the Al3Sc phase. Using the resulting dataset, the lattice mismatch between the Al3Sc precipitates and the (Al) matrix phase was calculated at different temperatures and different Ti and Zr contents. The lattice mismatch would be useful for estimating the critical size at which precipitates start to loss coherency.