Al–Cr–Fe phase diagram. Isothermal Sections in the region above 50 at% Al

Abstract The Al–Cr–Fe phase diagram was studied in the compositional range of 50–100 at% Al and partial isothermal sections were determined at 1160, 1100, 1075, 1042, 1000, 900, 800 and 700 °C. In the low-Al part of the studied compositional region the isostructural high-temperature Al–Cr and Al–Fe γ 1 -phases form a continuous region of solid solutions. Both binary Al 13 Fe 4 and Al 5 Fe 2 were found to dissolve up to 6.5 at% Cr while Al 2 Fe was found to extend up to 4.1 at% Cr. The solid solutions based on the Al–Cr γ 2 and μ phases were determined to reach 35.2 and 1.3 at% Fe, respectively. The dissolution of Cr in the Al–Fe binaries only slightly influences their Al concentrations, while the Al–Cr binaries exhibit decreasing Al concentration with increasing Fe concentration. The Al–Cr η -phase dissolves up to 5 at% Fe, which results in a sharp decrease of its Al concentration and increase of melting temperatures. The earlier reported existence of a ternary decagonal D 3 -phase and three complex periodic phases O 1 , H and e was confirmed and their compositions at different temperatures were specified.