Al-rich region of Al–Cu–Mn

The Al-Cu-Mn alloy system was studied above 45 at.% Al between 550 and 910 degrees C by scanning electron microscopy, powder X-ray diffraction and differential thermal analysis. A wide ternary region of the so-called beta-phase extending along similar to 50 at.% Al was confirmed. It has a CsCl-type structure with a approximate to 0.292-0.298 nm. The total gamma(1)/gamma(2)-region extends from Al-Mn up to similar to 17 at.% Cu and the high-temperature T-Al3Mn phase (Pnma, a approximate to 1.48, b approximate to 1.24, c approximate to 1.25 nm) extends up to similar to 15 at.% Cu. The so-called R-phase (Bbmm, a approximate to 2.41, b approximate to 1.25, c approximate to 0.76 nm) was found to exist in a compositional region of Al74-80Cu5-12.5Mn12.5-18. The ternary phase earlier reported at Al57.9Cu26.3Mn15.8 was confirmed. It exists below 697 degrees C in a compositional region of Al55-58Cu29-Mn-37(7.5-14). The decagonal D-3-phase was concluded to be stable in a compositional region of Al61.5-68.5Cu19-29.5Mn9-16. Below 631 degrees C an fcc phase (a = 0.5814 nm) was revealed around similar to Al60Cu36.5Mn3.5. Partial isothermal sections at 550, 600, 650, 750, 850 and 910 degrees C were constructed. (C) 2016 Elsevier B.V. All rights reserved.