Al–Cr–Fe phase diagram. Isothermal Sections in the region above 50 at% Al D. Pavlyuchkov a,b,c,n , B. Przepiórzyński c,d,1 , W. Kowalski c,d,2 , T.Ya. Velikanova a , B. Grushko c a I.N. Frantsevich Institute for Problems of Materials Science, Department of Physical Chemistry of Inorganic Materials, 03680 Kiev 142, Ukraine b Technical University of Freiberg, Institute of Materials Science, D-09599 Freiberg, Germany c IFF 3 , Forschungszentrum Jülich, D-52425 Jülich, Germany d Institute of Materials Science, University of Silesia, 40007 Katowice, Poland article info Article history: Received 25 February 2013 Received in revised form 6 November 2013 Accepted 18 December 2013 Available online 1 January 2014 Keywords: Phase diagram Transition metals aluminides Quasicrystals 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 1C. 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 ε was confirmed and their compositions at different temperatures were specified. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction The Al–Cr–Fe alloy system has been studied since the 1930 s and the relevant literature up to 2003 was reviewed in Ref. [1]. More recent investigations in Ref. [2–8] revealed significant differences of its constitution from that presented in Ref. [1]. Particularly, several phases were revealed in a wide compositional range associated in Ref. [9] with the ternary extension of the hexagonal μ-Al 4 Cr phase. In Ref. [5] the μ-phase was found to dissolve only up to  1 at% Fe, while at slightly higher Fe concentration a ternary ε-phase, similar to that in Al–Ni–Cr [10], is formed in a small compositional region. At still higher Al concentrations a significant part of this composi- tional region is occupied by an orthorhombic O 1 -phase [3] and then by a quasiperiodic decagonal D 3 -phase [3,4]. At higher Al concen- trations a new ternary hexagonal H-phase was found to be formed somewhat below 1000 1C [2]. Additionally, the binary η-Al 11 Cr 2 phase was found to extend up to  5 at% Fe [5]. Meanwhile the constitution of the binary boundary Al–Cr system was also significantly modified on the basis of the results of Ref. [11–13], and the binary boundary Al–Fe phase diagram was specified in Ref. [14,15]. The structure of the high-temperature Al–Fe є-phase, which had remained unknown for a long time, was found in Ref. [15] to be of a cubic γ-brass type, i.e. the same as the high-temperature Al–Cr γ 1 -phase [11]. This is favorable for the formation of a continuous region of solid solutions between these binaries. This suggestion was experimentally verified only recently in Ref. [7,8]. The latter study allowed the solidus and liquidus projections of Al–Cr–Fe to be constructed in the compositional region above 50 at% Al including the above-mentioned ternary phases. In the present contribution, continuing from those of Ref. [2–5,7,8], we present a series of partial isothermal sections of the Al–Cr–Fe phase diagram in the compositional region above 50 at% Al. 2. Experimental The alloys were produced from the constituent elements by levitation induction melting in a water-cooled copper crucible Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/calphad CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 0364-5916/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.calphad.2013.12.007 n Corresponding author at: Technical University of Freiberg, Institute of Materials Science, Gustav-Zeuner-Strasse 5, D-09599 Freiberg, Germany. Tel.: 49 3731 393641; fax: 49 3731 393657. E-mail address: d.pavlyuchkov@gmail.com (D. Pavlyuchkov). 1 Present address: Tenneco Automotive Eastern Europe Sp. z o.o., PL-44-100 Gliwice, Poland. 2 Present address: Institute of Physics, Polish Academy of Science, PL-02-668 Warsaw, Poland. 3 Presently PGI-5. CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 45 (2014) 194–203