Abstract
The continuous cooling from 1300 °C to ambient temperature by a differential thermal analyser was used to estimate the non-equilibrium evolution of phases in alloys Al₆₇Pd_14.6Co_18.4, Al₇₆Pd₁₁Co₁₃, Al_71.7Pd_14.4Co_13.9, and Al_67.4Pd_20.6Co₁₂. To compare non-equilibrium and near-equilibrium microstructures, the same alloys were also annealed at 850 °C for 500 h. Besides the differential thermal analysis, the X-ray diffraction, the scanning electron microscopy including energy dispersive X-ray spectroscopy, and the Vickers microhardness test were used in the investigation. Various combinations of phases β, U, δ, ε_n, F, Al₅Co₂, and Al₉Co₂ were identified in the alloys; there was no difference between continuously cooled and as-annealed conditions in the phase occurrence. The alloys, as sequenced above, were considered to solidify through phases β + V (concurrently), F, V, and β, respectively. Temperature ranges of solidification were also estimated. Based on the experimental results and other available data, the sequences of non-equilibrium phase transitions were proposed for several alloys of the still less-known Al-Pd-Co system.

Key words
Al-Pd-Co, continuous cooling, phase characterisation, differential thermal analysis, phase evolution

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