Simple Metal and Binary Alloy Phases Based on the fcc Structure: Electronic Origin of Distortions, Superlattices and Vacancies

Degtyareva, V.F.; Afonikova, N. S.

doi:10.3390/cryst7020034

Cited by 9 publications

(8 citation statements)

References 43 publications

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“…As shown in Figure 7, the C atom vacancies appeared with the decrease of the x value. Degtyareva et al [37] held that vacancy is a key factor for the stability of the fcc structure. The amount of C atoms in the C atom vacancy structure was less than the structure without vacancy.…”

Section: Resultsmentioning

confidence: 99%

Shape-Controlled TiCx Particles Fabricated by Combustion Synthesis in the Cu-Ti-C System

et al. 2017

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TiC x particle-reinforced Cu-matrix composites were prepared in the Cu-TiC system by thermal explosion and hot press. Extracted TiC x particles with various shapes of in situ TiC x particles in the Cu-TiC system were observed through the Field Emission Scanning Electron Microscope (FESEM). It was found that octahedral and close-to-spherical, spherical or cubic TiC x could be fabricated by changing the C/Ti molar ratio and Cu content. Then, the effect of the C/Ti molar ratio and constituent element concentrations on the shape of in situ TiC x particles was determined: the shape of TiC x particles is octahedral at a C/Ti ratio of 0.4-0.6 with the presence of 70 vol% Cu; or spherical and close-to-spherical at 0.8-1.0 with the presence of 70 vol% Cu; or cubic at C/Ti ratios ≥1.0 with the presence of Cu from 80 vol%-90 vol% and even at C/Ti ratios >1.0 with the presence of 70 vol% Cu. The shape-controlled synthesis of TiC x particles in the Cu-TiC system is realized.

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Section: Resultsmentioning

confidence: 99%

Shape-Controlled TiCx Particles Fabricated by Combustion Synthesis in the Cu-Ti-C System

et al. 2017

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“…These cases are constructed with the BRIZ program by proper choice of presentations: "sphere inside polyhedron" or "polyhedron inside sphere". Structural stabilization due to the electronic band contribution where FS is enveloping the BZ was discussed for phase stability in In and Sn alloys [22][23][24] and for fcc-based phases in simple metals [25].…”

Section: Theoretical Background and Methods Of Analysismentioning

confidence: 99%

“…Interestingly, the forms of the Brillouin zones with faces (8 8 0) and (11 3 3) for Cu 4 Cd 3 and Mg 28 Al 45 are similar (Figure 1) and related to the BZ for γ-brass with faces (3 3 0) and (4 1 1), which indicates the structural relationship between all these compounds. Structural presentations of complex intermetallics as multi-fold supercells of basic metallic close-packed lattices were considered in [25,41].…”

Section: Similar Structural Features Of Intermetallics With Giant Unimentioning

confidence: 99%

Structurally Complex Frank–Kasper Phases and Quasicrystal Approximants: Electronic Origin of Stability

Degtyareva

Afonikova

2017

Crystals

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Metal crystals with tetrahedral packing are known as Frank-Kasper phases, with large unit cells with the number of atoms numbering from hundreds to thousands. The main factors of the formation and stability of these phases are the atomic size ratio and the number of valence electrons per atom. The significance of the electronic energy contribution is analyzed within the Fermi sphere-Brillouin zone interaction model for several typical examples: Cu 4 Cd 3 , Mg 2 Al 3 with over a thousand atoms per cell, and for icosahedral quasicrystal approximants with 146-168 atoms per cell. Our analysis shows that to minimize the crystal energy, it is important that the Fermi sphere (FS) is in contact with the Brillouin zones that are related to the strong diffraction peaks: the zones either inscribe the FS or are circumscribed by the FS creating contact at edges or vertices.

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“…It consists of primary β dendrites in a lamellar eutectic (α + η) matrix. The β phase, which is unstable below 275 • C, decomposed to form a Zn-rich η equilibrium phase and an Al-rich α equilibrium phase, following the eutectoid reaction in the Zn-Al binary phase diagram [31][32][33].…”

Section: The Core/shell Za-8/alumina Powdermentioning

confidence: 99%

Sol–Gel Encapsulation of ZnAl Alloy Powder with Alumina Shell

Svetlizky

Eliaz

2021

Coatings

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Additive manufacturing (AM), for example, directed energy deposition (DED), may allow the processing of self-healing metal–matrix composites (SHMMCs). The sealing of cracks in these SHMMCs would be achieved via the melting of micro-encapsulated low melting point particulates (LMPPs), incorporated into the material during AM, by heat treatment of the part during service. Zn-Al alloys are good candidates to serve as LMPPs, for example, when the matrix of the MMC is made of an aluminum alloy. However, such powders should first be encapsulated by a thermal and diffusion barrier. Here, we propose a sol–gel process for encapsulation of a custom-made ZA-8 (Zn92Al8, wt.%) core powder in a ceramic alumina (Al2O3) shell. We first modify the surface of the ZA-8 powder with (12-phosphonododecyl)phosphonic acid (Di-PA) hydrophobic self-assembled monolayer (SAM) in order to prevent extensive hydrogen evolution and formation of non-uniform and porous oxide/hydroxide surface layers during the sol–gel process. Calcination for 1 h at 500 °C is found to be insufficient for complete boehmite-to-γ(Al2O3) phase transformation. Thermal stability tests in an air-atmosphere furnace at 600 °C for 1 h result in melting, distortion, and sintering into a brittle sponge (aggregate) of the as-atomized powder. In contrast, the core/shell powder is not sintered and preserves its spherical morphology, with no apparent “leaks” of the ZA-8 core alloy out of the ceramic encapsulation.

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Simple Metal and Binary Alloy Phases Based on the fcc Structure: Electronic Origin of Distortions, Superlattices and Vacancies

Cited by 9 publications

References 43 publications

Shape-Controlled TiCx Particles Fabricated by Combustion Synthesis in the Cu-Ti-C System

Shape-Controlled TiCx Particles Fabricated by Combustion Synthesis in the Cu-Ti-C System

Structurally Complex Frank–Kasper Phases and Quasicrystal Approximants: Electronic Origin of Stability

Sol–Gel Encapsulation of ZnAl Alloy Powder with Alumina Shell

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