On the constitution of the Al-rich part of the Al–Cr–Mn system

The constitution of the Al–Cr–Mn phase diagram in the compositional range of 60–100 at.% Al was investigated between 560 and 1010 °C. Continuous ternary solid solution ranges were confirmed between the isostructural binary hexagonal μ-Al4Cr and μ-Al4Mn phases, between the triclinic low-temperature Al11Mn4 and Al3Cr phases, between the high-temperature cubic γ1-phases and between the low-temperature rhombohedral γ2-phases. The range of the Al–Cr θ-phase was found to extend up to 7.3 at.% Mn and that of the Al–Cr η-phase up to 15 at.% Mn. The dissolution of Mn decreases the melting temperatures of the θ-phase and η-phases. Of the Al–Mn phases, the high-temperature Al3Mn phase (T-phase) dissolves up to 12.5 at.% Cr, λ-Al4Mn up to 3 at.% Cr, Al6Mn less than 1 at.% Cr, while Al12Mn (G-phase) up to 4.7 at.% Cr. The dissolution of Cr increases the melting temperatures of the λ-phase and G-phase.