Phase equilibria between 540 and 1010 deg C were studied in Al-Cu-Rh alloys containing more than 50 at percent Al. Congruent equiatomic AlRh dissolves more than 40 at percent Cu and extends up to 58 at percent Al at the high-Cu part of its compositional range. High-temperature cubic C-Al_5Rh_2 (C-phase) dissolves up to 13 at percent Cu, "A_3Rh" (epsilon_6-phase) up to 15 at percent Cu and Al_9Rh_2 up to 1.5 at percent Cu. The solubility of the third element in other binary Al-Rh and Al-Cu phases is below 0.5 at. percent. Close to the high-Cu limit of the C-phase region the fcc C_2-phase structurally related to the C-phase is formed. Stable decagonal phase (D_1-phase) is formed below 1005 deg C in a compositional range extending from Al_(65)Cu_(16)Rh_(19) to Al_(62)Cu_(23)Rh_(15), which shifts to higher Cu concentrations with decreasing temperature. An additional ternary phase forming around the Al_(70)Cu_(20)Rh_(10) composition below 660 deg C was revealed. Partial 1010, 990, 900, 800, 700, 600 and 540 deg C isothermal sections were determined.
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