The Al-rich region of the Al–Fe–Mn alloy system

•Constitution of Al–Fe–Mn was studied above 50at.% Al at 650–1070°C.•AlMn (A2) and AlFe (B2) phases form a continuous compositional region.•Al8Mn5 and Al8Fe5 γ-brass type phases form a continuous compositional region.•Al13Fe4, Al5Fe2, Al2Fe, Al6Mn, Al11Mn4, γ2 exhibit wide ternary extensions.•Four ternary intermetallics were revealed. Phase equilibria in the Al-rich region of the Al–Fe–Mn alloy system were studied at 1070, 1020, 950, 875, 800, 740, 695 and 650°C. The continuous region of the bcc solid solution was estimated between the Al–Mn and Al–Fe terminals. Also the isostructural high-temperature Al–Mn and Al–Fe γ1-phases (γ-brass type structure) form continuous regions. The Al6Mn, high-temperature T-Al11Mn4 and low-temperature γ2 phases dissolve up to 9.0, 14.5 and 31.0at.% Fe, respectively, while the M-Al13Fe4, Al5Fe2 and Al2Fe phases dissolve up to 15.5, 11.5 and 10.0at.% Mn, respectively. The thermodynamically stable decagonal D3-phase with periodicity of 1.25nm in the specific direction and two periodic intermetallics designated φ (P63/mmc; a=0.7554, c=0.7872nm) and κ (P63/m; a=1.7630, c=1.2506nm) were identified. An additional ternary phase of unknown structure was also revealed.