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 3Ni 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 82Ni 3Cr 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 80Ni 9Cr 11.