An investigation of the
Al-rich region of the Al-Cu-Ir phase diagram
Chem.
Met. Alloys 2
(2009) 30-33
https://doi.org/10.30970/cma2.0083
D. KAPUSH, B. GRUSHKO, D. PAVLYUCHKOV, T.Ya. VELIKANOVA
The Al-Cu-Ir alloy system
was studied in the range above 35 at.% Al. Partial 900
and 540°C isothermal sections were
determined. Congruent equiatomic AlIr
extends at approximately constant Al concentration up to 30 at.% Cu. Cubic C-Al2.7Ir (C-phase) dissolves up to
12 at.% Cu, Al3Ir up to 8.5 at.% Cu, Al28Ir9
(χ-phase) and Al45Ir13 (φ-phase) up to 3 at.%
Cu, and Al9Ir2 up
to 2.5 at.% Cu. Increase of the Cu concentration results in a decrease of the
Al concentration of these phases. The Al-Cu º1-phase dissolves up to
3 at.% Ir, while the
solubility of Ir in θ and η2 is
below 0.5 at.%. Close to the high-Cu limit of the C-phase region an fcc C2-phase (Fm3, a = 1.53928 nm) structurally
related to the C-phase is formed. A stable decagonal phase (D1-phase)
is formed below 1002ºC in a compositional range extending from Al61.5Cu20Ir18.5
to Al59Cu25.5Ir15.5. A ternary orthorhombic
ε6-phase (a = 2.34
nm, b = 1.65 nm, c = 1.24 nm) was found below
~1200ºC in a compositional range extending from Al71.5Cu6Ir22.5
to Al68Cu12.5Ir19.5. An additional ternary
ω-phase (P4/mnc,
a = 0.6414 nm, c = 1.4842
nm) forming around the Al70Cu20Ir10
composition below 683ºC was revealed.
Partial isothermal section at 900°C. The compositions of the studied
samples are shown by spots. Provisional tie-lines are shown by broken lines. L
is liquid. The compositional region marked by (?) was not studied.
Keywords
Phase diagram / Intermetallics
/ Quasicrystals