Phase equilibria of the Al–Mn–Zn system at 600 °C

The phase equilibria at 600 °C of the Al–Mn–Zn system were investigated with 38 alloys, by means of X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and electron probe microanalysis. Five ternary phases, denoted as T1, T2, T3, T4 and γ3, were found at 600 °C. T1 extends approximately at a constant Mn content and has a composition range from 73.6 to 79.8 at.% Al. T3 and T4 have composition ranges from about 67.1 to 70.1 at.% Al and from about 61.5 to 67.6 at.% Al, respectively. Three ternary compounds of τ1 (Mn5ZnAl24), τ2 (Mn2ZnAl9) and τ3 (Mn3Zn2Al11), which had been reported in the literature, were not detected in the present work. An extensive homogeneity range of the γ3 phase was observed at 600 °C. This phase is isomorphic to the binary Mn5Zn21 compound, which is stable only below 420 °C, and is stabilized by the Al addition in the ternary system. The sixteen three-phase equilibria were determined and the isothermal section was constructed at 600 °C.

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► The isothermal section at 600 °C of the Al–Mn–Zn system was determined.
► Five ternary phases, denoted as T1, T2, T3, T4 and γ3, were found at 600 °C.
► Four of the ternary phases, T1, T2, T3 and T4, are assumed to be the newly found ternary phases.