Refinement of the Al-rich part of the Al–Cu–Re phase diagram and atomic model of the ternary Al6.2Cu2Re phase

• Al–Cu–Re was studied at 540–1030 °C up to 25 at% Re and 60 at% Cu.
• Al11Re4, h-Al4Re and l-Al4Re dissolve 6, 4.5 and 2.3 at% Cu, respectively.
• Earlier reported ternary compound Al8CuRe was not confirmed.
• Earlier reported ternary compound Al7Cu2Re is probably Al6.2Cu2Re.
• Crystal structure of hexagonal Al6.2Cu2Re was solved.

Partial isothermal sections at 800, 650 and 590 °C were constructed for an Al-rich compositional range of Al–Cu–Re. The maximal solubility of Cu in the Al11Re4, h-Al4Re and l-Al4Re phases was found to be ∼6, 4.5, and 2.3 at% respectively, while the solubility of Re in the Al–Cu θ, η1 and ε2 phases was below 0.5 at%. Below 740 °C, a ternary hexagonal phase (P63, a = 1.1029 and c = 1.2746 nm) is formed in a small compositional range close to Al65Cu25Re10. Its structural model was deduced by direct methods applied on the precession electron diffraction tomography data.