Phase transitions in selected Al-Pd-Co alloys during continuous cooling

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 Al67Pd14.6Co18.4, Al76Pd11Co13, Al71.7Pd14.4Co13.9, and Al67.4Pd20.6Co12. 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, εn, 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. K e y w o r d s : Al-Pd-Co, continuous cooling, phase characterisation, differential thermal analysis, phase evolution

Aqueous Corrosion of Aluminum-Transition Metal Alloys Composed of Structurally Complex Phases: A Review

“…The electron diffraction pattern of the QC (Figure 5a) has a perfect five-fold symmetry. The electron diffraction pattern of a quasicrystalline approximant (Figure 5b) with an orthorhombic unit cell has either two-fold or four-fold axis of symmetry, but there are indications of five-fold symmetry related to the icosahedral arrangement of atoms in clusters [10,11,[52][53][54][55][56][57][58][59].…”

“…Materials 2021, 14, 5418 6 of 29 symmetry, but there are indications of five-fold symmetry related to the icosahedral arrangement of atoms in clusters [10,11,[52][53][54][55][56][57][58][59]. The surface structure of SCIPs is significantly less understood compared to bulk [60,61].…”

Thermodynamic Modeling of the Al–Co–Pd Ternary System, Aluminum Rich Corner

“…The ternary system was experimentally studied by several authors in papers [7][8][9][10][11][12][13][14][15]. The main interest was given especially to the aluminum-rich region.…”

“…They published isothermal sections at 1323, 1273, 1213 and 1063 K for 50-100 at.% Al. Černičková et al studied the evolution of phases in several Al-Pd-Co alloys after longterm annealing [12] and during continuous cooling [13]. Černičková et al also focused on the homogeneity range of ε, U and F phases at 1123 K in the study [14].…”

“…Recently, a part of the isothermal section of the system at 1293 K was published by Ďuriška in the paper [15]. The mentioned authors [8][9][10][11][12][13][14][15] observed six equilibrium ternary phases (W, V, F, U, Y, C2) and structurally complex ε-family phases in the ternary system.…”