The phase diagram of the Al-Cu binary system was reinvestigated experimentally. The current study was designed to contribute to a better description of those parts of the phase diagram which are disputed in the current scientific literature, and in addition, to study the phase equilibria at 300 °C. The melting behavior of the θ-phase was confirmed to be peritectic. A metastable congruent solidification of the θ-phase was observed from the microstructural examination of as-cast samples. The location of the liquidus curve in this region of the phase diagram was more accurately defined using DSC measurements taken at slow-heating rates (1 °C min⁻¹). The temperature stability of the ζ-phase was reevaluated and was found to lie in the range 373–597 °C. The phase boundaries of the γ′ + ε′ two-phase field were experimentally defined. Difficulties in defining the γ′/δ transition were addressed by a combined EDX/XRD investigation of more than ten samples that had been annealed in the temperature range of 500 to 750 °C. The (γ′ + δ) two-phase field was postulated from XRD studies of quenched samples. The temperature of the ordering reaction γ ↔ γ′ within the γ(γ′) + β phase field was experimentally determined to be 779.6 °C. All other parts of the Al-Cu phase diagram studied here were found to be in very good agreement with the most recent previous descriptions.

The Al–Fe–Si system was studied for an isothermal section at 800 °C in the Al-rich part and at 900 °C in the Fe-rich part, and for half a dozen vertical sections at 27, 35, 40, 50 and 60 at.% Fe and 5 at.% Al. Optical microscopy and powder X-ray diffraction (XRD) was used for initial sample characterization, and Electron Probe Microanalysis (EPMA) and Scanning Electron Microscopy (SEM) of the annealed samples was used to determine the exact phase compositions. Thermal reactions were studied by Differential Thermal Analysis (DTA). Our experimental results are generally in good agreement with the most recent phase diagram versions of the system Al–Fe–Si. A new ternary high-temperature phase τ12 (cF96, NiTi2-type) with the composition Al48Fe36Si16 was discovered and was structurally characterized by means of single-crystal and powder XRD. The variation of the lattice parameters of the triclinic phase τ1 with the composition Al2+xFe3Si3−x (−0.3 < x < 1.3) was studied in detail. For the binary phase FeSi2 only small solubility of Al was found in the low-temperature modification LT-FeSi2 (ζβ) but significant solubility in the high-temperature modification HT-FeSi2 (ζα) (8.5 at.% Al). It was found that the high-temperature modification of FeSi2 is stabilized down to much lower temperature in the ternary, confirming earlier literature suggestions on this issue. DTA results in four selected vertical sections were compared with calculated sections based on a recent CALPHAD assessment. The deviations of liquidus values are significant suggesting the need for improvement of the thermodynamic models.

► Complete reinvestigation of the Al–Cu phase diagram. ► Several new phase equilibria established. ► Structure of η1 solved by high temperature XRD.

A thermodynamic assessment of the Bi¿Sn¿Zn ternary system was carried out using the CALPHAD approach along with thermodynamicdescriptions from new assessments of the Bi¿Sn and Bi¿Zn systems. Selected experimental data from the literature and our own work were alsoused. New sets of optimized thermodynamic parameters were obtained that lead to a very good fit between the calculated and experimental data.The Bi¿Sn¿Zn system is one of the candidates for lead-free solder materials