An investigation of the Al–Cu–Cr phase diagram: Phase equilibria at 800–1000 °C

The Al–Cu–Cr alloy system was investigated at 800–1000 °C. The Al–Cr γ-range extends up to 18 at.% Cu, extensions of other binary phases are below 3 at.% of the third element. The stability of quasiperiodic decagonal phases reported in the literature was not confirmed at the temperatures studied. The formation of three ternary phases was observed: in addition to a hexagonal phase with a ≈ 1.77 and c ≈ 1.26 nm, and a cubic phase with a ≈ 1.82 nm reported earlier, also a primitive cubic phase with a ≈ 0.30 nm was revealed in the region of the Al46Cu36Cr18 composition. The latter phase only exists in a small temperature range around 900 °C. The isothermal section at 1000 °C and the partial isothermal sections at 900 and 800 °C were constructed.