4^th International Aluminium Lithium Conference

J. Phys. Colloques 48 (1987) C3-473-C3-479
DOI: 10.1051/jphyscol:1987354

EXPERIMENTAL STUDY AND THERMODYNAMIC CALCULATION OF THE Al-Li-Mg EQUILIBRIUM PHASE DIAGRAM

B. DUBOST¹, P. BOMPARD² et I. ANSARA<sup>3

1</sup>  Cégédur-Péchiney, Centre de Recherche et Développement, B.P. 27, F-38340 Voreppe, France
²  Laboratoire de Métallurgie, Ecole Centrale des Arts et Manufactures, Grande Voie Vignes, F-92295 Châtenay-Malabry Cedex, France
³  Laboratoire de Thermodynamique et de Physico Chimie Métallurgiques, ENSEEG, B.P. 75, F-38402 Saint-Martin-d'Hères Cedex, France

Abstract
A thorough study of the Al-Li-Mg equilibrium phase diagram in the Al-rich corner is described. An experimental approach of the constitution of this system by thermal analysis, metallography and microanalysis is combined to a thermodynamic calculation based on literature data, intermetallic compound recognition and a study of liquid-solid phase equilibria (monovariant and invariant reactions). Ternary or quasi-binary interactions involving the Al₂LiMg and (Mg, Li)17Al₁₂ compounds are considered in addition to relevant results on the binary constitutive systems (Al-Li, Al-Mg). Using a relatively limited number of cast alloy samples, the ternary Al-Li-Mg equilibrium phase diagram is calculated over wide temperature and composition ranges (Li, Mg ≤ 50 at % ; 300°C ≤ T ≤ 650°C) and compares satisfactorily with the literature and experimental results.