Stabilizing effect of alloying elements on metastable phases in cast aluminum alloys by CALPHAD calculations

Anass Assadiki (1, 2) , Vladimir A. Esin (1) , Miguel Bruno (1) , Rémi Martinez (2)

1 CDM - Centre des Matériaux
2 Fonderie Montupet

Thermo-Calc software equipped with its TCAL4.0 database for aluminum alloys was used to investigate the influence of a number of alloying elements on the temperature stability of metastable phases such as -Al2Cu and -Mg2Si. These phases are well-known to provide precipitation hardening thus increasing the mechanical properties of cast aluminum alloys for cylinder heads application. Two categories of elements are identified depending on their influence on the metastable phases stability: (i) destabilizing or non-stabilizing (Li, Hf, Cr and Ce) and (ii) stabilizing (V, Ti, Cr, and Sc). According to the thermodynamic calculations, Ti has the strongest stabilizing effect on -Al2Cu and -Mg2Si as well as on their precursors. The computed predictions are compared with data obtained by DSC and the Ti effect on the temperature stability of metastable phases is confirmed experimentally.

Mots clés: Cast aluminum alloy; Hardening; Aging; Metastable equilibrium; CALPHAD

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Anass Assadiki, Vladimir A. Esin, Miguel Bruno, Rémi Martinez. Stabilizing effect of alloying elements on metastable phases in cast aluminum alloys by CALPHAD calculations. Computational Materials Science, 2018, 145, pp.1-7. ⟨10.1016/j.commatsci.2017.12.056⟩. ⟨hal-01722934⟩