A study of the Al-rich region of the Al–Fe–Ir alloy system

Abstract

Phase equilibria in Al–Fe–Ir were studied at 850 and 1100 °C above 50 at% Al. The formation of the continuous ternary region of solid solutions was estimated along about 50 at% Al between the Al–Fe and Al–Ir β-phases. The binary M-Al13Fe4 and Al5Fe2 phases dissolve up to at least 10 and 5 at% Ir, the CIr-phase, Al3Ir, χIr-phase and Al9Ir2 up to ∼4, ∼9, ∼2.5 and at least 2.5 at% Fe, respectively. These binaries extend to the ternary compositions at approximately constant Al. Three ternary phases designated m, Ł and N were revealed. The m-Al13(Fe,Ir)4 phase of the Al13Os4-type structure (C2/m, a = 1.7406 nm, b = 0.41923 nm, c = 0.76459 nm, β = 115.78°) is formed at ∼Al75–76Fe6–9Ir18–15. A ternary hexagonal Ł-phase (a = 1.09034 nm, c = 0.77614 nm) is formed in a small compositional region around ∼ Al74Fe14Ir12. The structure of a complex ternary N-phase forming at ∼Al77.5Fe5.0–10.5Ir17.5–12 was not specified.