A study of phase equilibria in the Al-rich part of the Al-Mn alloy system

Following new findings by Y. Du et al. (Int. J. Mater. Res. 98 (2007) 855), the Al-Mn phase diagram was re-examined in the compositional range of similar to 4 to 27 at.% Mn using scanning and transmission electron microscopy, energy-dispersive X-ray analysis and differential thermal analysis. The Corrections to the Al-Mn phase diagram concerning the reactions involving the Al(6)Mn and Al(4)Mn phases reported in the above-mentioned contribution were not confirmed. Instead, our results were in agreement with those reported earlier by Murray et al. (Metall. Trans. A18 (1987) 385): the reaction Al(6)Mn + mu <-> lambda occurs at 695 degrees C, and L + mu <-> AL(6)Mn at 705 degrees C. At higher Al concentrations, the reactions mu <-> L + T, mu + nu <-> T and T <-> L + gamma(1) were revealed at similar to 923, 913 degrees C and 1001 degrees C, respectively, in good agreement with the literature data. Kinetic effects during phase transitions of the Al-Mn alloys are discussed on the basis of experimental results.