Complex ɛ-phases in the Al–Pd-transition–metal systems: Towards a combination of an electrical conductor with a thermal insulator

Smontara, Ana; Bilušić, Ante; Grushko, B.; Balanetskyy, S.; Jagličić, Zvonko; Vrtnik, S.; Dolinšek, J.

doi:10.1016/j.jallcom.2006.11.097

Cited by 11 publications

(5 citation statements)

References 30 publications

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“…In fact, the size of the whole grown crystal is the size of the cell. These large unit cells are in contrast to other metallic materials, whose unit cells are built from small number of atoms [48].…”

Section: Crystal Structure Of Quasicrystals and Their Approximantsmentioning

confidence: 96%

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

et al. 2021

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Complex metallic alloys (CMAs) are materials composed of structurally complex intermetallic phases (SCIPs). The SCIPs consist of large unit cells containing hundreds or even thousands of atoms. Well-defined atomic clusters are found in their structure, typically of icosahedral point group symmetry. In SCIPs, a long-range order is observed. Aluminum-based CMAs contain approximately 70 at.% Al. In this paper, the corrosion behavior of bulk Al-based CMAs is reviewed. The Al–TM alloys (TM = transition metal) have been sorted according to their chemical composition. The alloys tend to passivate because of high Al concentration. The Al–Cr alloys, for example, can form protective passive layers of considerable thickness in different electrolytes. In halide-containing solutions, however, the alloys are prone to pitting corrosion. The electrochemical activity of aluminum-transition metal SCIPs is primarily determined by electrode potential of the alloying element(s). Galvanic microcells form between different SCIPs which may further accelerate the localized corrosion attack. The electrochemical nobility of individual SCIPs increases with increasing concentration of noble elements. The SCIPs with electrochemically active elements tend to dissolve in contact with nobler particles. The SCIPs with noble metals are prone to selective de-alloying (de–aluminification) and their electrochemical activity may change over time as a result of de-alloying. The metal composition of the SCIPs has a primary influence on their corrosion properties. The structural complexity is secondary and becomes important when phases with similar chemical composition, but different crystal structure, come into close physical contact.

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Section: Crystal Structure Of Quasicrystals and Their Approximantsmentioning

confidence: 96%

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

et al. 2021

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“…Thermodynamic assessment for the Al-Co-Pd ternary system has not yet been published. However, the system is of interest for the possible use of the Al-Pd based materials, for example, for catalysts [1] or as coatings with good oxidation resistance, low adhesion and high hardness [2][3][4] and also in electronics as semiconductors [5,6]. In addition, the system is also interesting from a scientific point of view because it contains a large number of complicated intermetallics, quasicrystals and quasi-crystalline approximants [7,8].…”

Section: Introductionmentioning

confidence: 99%

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

Homolová

Kroupa

2021

Metals

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The aluminum-rich corner of the Al–Co–Pd ternary system was thermodynamically modeled by the CALPHAD method in the present study. The ternary system is a complex system with many ternary phases (W, V, F, U, Y2, C2). All ternary phases, except phase U, were modeled as stoichiometric compounds. The order–disorder model was used to describe the BCC–B2 and BCC-A2 phases. Solubility of the third element in binary intermetallic phases (Al5Co2, Al3Co, Al9Co2, Al13Co4, Al3Pd and Al3Pd2) was modeled. The experimental results collected from the literature were used in the optimization of the thermodynamic parameters. A good agreement between the experimental results and the calculations was achieved.

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“…In Al-Pd alloys, the following phases have been identified [7]: (Al), λ-Al 4 Pd, γ-Al 21 Pd 8 , ε 6 and ε 28 (both ~Al 3 Pd), δ-Al 3 Pd 2 , β-AlPd, β'-AlPd, µ-AlPd, υ-Al 3 Pd 5 , ρ-AlPd 2 , τ-Al 2 Pd 5 , and (Pd). The metallographically non-distinguishable phases ε 6 and ε 28 [8] are quasicrystalline approximants of orthorhombic structure, both exhibiting giant unit cells [9]. In this work, they are jointly denoted as ε n .…”

Section: Introductionmentioning

confidence: 99%

“…In the Al-Pd alloy system, ε n is formed below about 790°C. It has, for instance, a low thermal conductivity combined with a moderate electrical resistivity [9]. Some of structurally complex intermetallic phases have a rich variety of different adsorption sites [10]; as such, they are interesting for catalysis [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical corrosion of Al-Pd alloys in HCl and NaOH solutions

Palcut

Ďuriška

Spoták

et al. 2017

J min metall B Metall

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The corrosion performance of as-solidified Al-Pd alloys in HCl and NaOH aqueous solutions is investigated in this work. Four different alloys (Al 88 Pd 12 , Al 77 Pd 23 , Al 72 Pd 28 and Al 67 Pd 33 , element concentrations are given in at.%) were prepared from high purity Al and Pd lumps by arc-melting in Ar. Subsequently, the alloy microstructure and phase occurrence were investigated by a combination of scanning electron microscopy and room-temperature powder X-ray diffraction. The assolidified Al-Pd alloys were found to consist of several single-phase microstructure constituents with various structures and chemical compositions, including structurally complex intermetallic phases. The polished surfaces of the Al-Pd alloys were subjected to electrochemical polarization in aqueous HCl and NaOH solutions (0.01 mol.dm-3) at 21±2°C. The corrosion experiments were conducted in a standard 3-electrode cell controlled by potentiostat. The corrosion potentials and corrosion current densities were determined by Tafel extrapolation of the experimental polarization curves. Phase dissolution has been observed on the alloy surfaces and some of the phases were preferentially corroded. The effects of the alloy microstructure and the phase occurrence are evaluated. The local nobility of individual intermetallic compounds is discussed. Finally, the conclusions for the alloys corrosion performance in acidic and basic solutions are provided.

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Complex ɛ-phases in the Al–Pd-transition–metal systems: Towards a combination of an electrical conductor with a thermal insulator

Cited by 11 publications

References 30 publications

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

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

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

Electrochemical corrosion of Al-Pd alloys in HCl and NaOH solutions

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