Experimental determination and thermodynamic reassessment of the Al–Cr–Ru ternary system

The isothermal sections at 950 °C and 1150 °C of Al–Cr–Ru ternary system were determined experimentally by equilibrium alloy method, combined with X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometric. Nine and eight three-phase equilibria were confirmed at the 950 °C and 1150 °C isothermal sections of the Al–Cr–Ru ternary systems, respectively. The liquids surface projection of the Al–Cr–Ru ternary system was determined by identifying the microstructures of the as-cast alloys, and seven primary solidification regions were determined in the liquids surface projection. Besides, the ternary compound τ2 was identified as end-centered monoclinic structure by transmission electron diffraction analysis. The lattice parameters of the τ2 phase are a = 0.5175 nm, b = 1.7532 nm, c = 0.5150 nm and α = γ = 90°, β = 79.167°. Based on the available data of the Al–Cr–Ru ternary system and related binary systems, thermodynamic reassessment of the Al–Cr–Ru ternary system was performed using the Calculation of Phase Diagram approach. A new thermodynamic database for the Al–Cr–Ru ternary system was obtained, and the experimental data are consistent well with the calculated results.