Thermodynamic reassessment of the Al–Cr–Si system with the refined description of the Al–Cr system

• Three Al–Cr alloys were investigated via XRD to verify the existence of Al11Cr4.
• The Al–Cr system was remodeled with new sublattice models for γ-H and γ-L.
• Noticeable improvements have been made compared with the previous modeling.
• The ΔfH for τ1 and τ2 at 0 K were computed via the first-principles calculations.
• An optimal set of thermodynamic parameters of the Al–Cr–Si system was obtained.

Three alloys in the Al–Cr system were investigated by means of X-ray diffraction (XRD) in order to verify the existence of the reported new phase Al11Cr4. The XRD results showed no evidence for the existence of the so-called new phase Al11Cr4. Based on the critically reviewed experimental data available in the literature and the present experimental results, the Al–Cr system was re-optimized using the CALPHAD approach with sublattice models (Al,Cr)2(Al,Cr)3(Cr)2(Al)6 for γ-H (high temperature phase) and (Al)12(Cr)5(Al,Cr)9 for γ-L (low temperature phase) according to their respective crystal structures. Subsequently, a thermodynamic description of the Al–Cr–Si system was obtained over the entire composition range based on the present thermodynamic description of the Al–Cr system, the previous descriptions for the Al–Si and Cr–Si systems as well as the experimental data from the literature. The present thermodynamic modeling can satisfactorily account for most of the reliable experimental data in this ternary system.