Al‐Rich Region of the Al—Ni—Cr Alloy System Below 900 °C.

Abstract The region of Al–Ni–Cr above 60 at.% Al was specified at 700–900 °C. In total, the ternary extensions of the binary Al–Cr phases were found to be: the θ-phase up to 2 at.% of Ni, the η-phase, μ-phase and ν-phase up to 1 at.% of Ni and the γ-phase(s) up to 3 at.% of Ni. The binary Al 3 Ni phase dissolves around 1 at.% of Cr and the Al–Ni δ-phase up to ∼3 at.% of Cr. In addition to the reported earlier ternary ζ-phase (hexagonal, a  ≈ 1.78, c  ≈ 1.23 nm) and ɛ-phase (orthorhombic, a  ≈ 1.26, b  ≈ 3.48, c  ≈ 2.02 nm), two ternary phases designated ζ 1 and ϕ were confirmed. The ζ 1 -phase is stable at 700 and 800 °C in a compositional range around Al 82 Ni 3 Cr 15 . Its structure is closely related to the structure of the ζ-phase. A rhombohedral lattice with a  ≈ 2.87 nm, α  ≈ 36° ( a  ≈ 1.77 and c  ≈ 8.04 nm in the hexagonal coordinates) was associated with this phase. The ϕ-phase (monoclinic, a  ≈ 1.33, b  ≈ 1.25, c  ≈ 1.25 nm and β  ≈ 100°) was found to be stable below 835 °C around Al 80 Ni 9 Cr 11 .