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

The phase equilibria at 600 degrees 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 T-1, T-2, T-3, T-4 and gamma(3), were found at 600 degrees C. T-1 extends approximately at a constant Mn content and has a composition range from 73.6 to 79.8 at.% Al. T-3 and T-4 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 tau(1) (Mn5ZnAl24), tau(2) (Mn2ZnAl9) and tau(3) (Mn3Zn2Al11), which had been reported in the literature, were not detected in the present work. An extensive homogeneity range of the gamma(3) phase was observed at 600 degrees C. This phase is isomorphic to the binary Mn5Zn21 compound, which is stable only below 420 degrees 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 degrees C. (C) 2013 Elsevier B.V. All rights reserved.