Analysis of the Ground State of a Solid Solution with Interactions up tok-th Coordination Spheres of the Crystal Lattice. Selection of the Subdivision of the Lattice into Sublattices

1984 ◽  
Vol 85 (1) ◽  
pp. 51-60 ◽  
Author(s):  
B. A. Men ◽  
M. L. Levitan
Keyword(s):  
Solid Solution ◽  
Crystal Lattice ◽  
Ground State ◽  
Coordination Spheres ◽  
Selection Of

scholarly journals Source coding by efficient selection of ground-state clusters

2005 ◽  
Vol 72 (1) ◽  
Author(s):  
Demian Battaglia ◽  
Alfredo Braunstein ◽  
Joël Chavas ◽  
Riccardo Zecchina
Keyword(s):  
Ground State ◽  
Source Coding ◽  
Efficient Selection ◽  
Selection Of

scholarly journals The Effect of High-Intensity Electron Beam on the Crystal Structure, Phase Composition, and Properties of Al–Si Alloys with Different Silicon Content

2021 ◽  
Vol 22 (1) ◽  
pp. 129-157
Author(s):  
D. V. Zaguliaev ◽  
S. V. Konovalov ◽  
Yu. F. Ivanov ◽  
V. E. Gromov ◽  
V. V. Shlyarov ◽  
...  
Keyword(s):  
Solid Solution ◽  
Electron Beam ◽  
Phase Composition ◽  
Crystal Lattice ◽  
High Intensity ◽  
Materials Science ◽  
Lattice Parameter ◽  
Crystal Lattice Parameter ◽  
Material Surface ◽  
Modified Layer

The study deals with the element–phase composition, microstructure evolution, crystal-lattice parameter, and microdistortions as well as the size of the coherent scattering region in the Al–10.65Si–2.11Cu and Al–5.39Si–1.33Cu alloys irradiated with the high-intensity electron beam. As revealed by the methods of x-ray phase analysis, the principal phases in untreated alloys are the aluminium-based solid solution, silicon, intermetallics, and Fe2Al9Si2 phase. In addition, the Cu9Al4 phase is detected in Al–10.65Si–2.11Cu alloy. Processing alloys with the pulsed electron beam induces the transformation of lattice parameters of Al–10.65Si–2.11Cu (aluminium-based solid solution) and Al–5.39Si–1.33Cu (Al1 and Al2 phases). The reason for the crystal-lattice parameter change in the Al–10.65Si–2.11Cu and Al–5.39Si–1.33Cu alloys is suggested to be the changing concentration of alloying elements in the solid solution of these phases. As established, if a density of electron beam is of 30 and 50 J/cm2, the silicon and intermetallic compounds dissolve in the modified layer. The state-of-the-art methods of the physical materials science made possible to establish the formation of a layer with a nanocrystalline structure of the cell-type crystallization because of the material surface irradiation. The thickness of a modified layer depends on the parameters of the electron-beam treatment and reaches maximum of 90 µm at the energy density of 50 J/cm2. According to the transmission (TEM) and scanning (SEM) electron microscopy data, the silicon particles occupy the cell boundaries. Such changes in the structural and phase states of the materials response on their mechanical characteristics. To characterize the surface properties, the microhardness, wear parameter, and friction coefficient values are determined directly on the irradiated surface for all modification variants. As shown, the irradiation of the material surface with an intensive electron beam increases wear resistance and microhardness of the Al–10.65Si–2.11Cu and Al–5.39Si–1.33Cu alloys.

The role of mineral nanoparticles at a fluid-magnetite interface: Implications for trace-element uptake in hydrothermal systems

2019 ◽  
Vol 104 (8) ◽  
pp. 1180-1188 ◽  
Author(s):  
Shuo Yin ◽  
Richard Wirth ◽  
Changqian Ma ◽  
Jiannan Xu
Keyword(s):  
Solid Solution ◽  
Crystal Lattice ◽  
Trace Element ◽  
Hydrothermal Systems ◽  
Oscillatory Zoning ◽  
Bulk Fluid ◽  
Continuous Increase ◽  
Interfacial Fluid ◽  
Spinel Nanoparticles

Abstract The migrating fluid-mineral interface provides an opportunity for the uptake of trace elements as solid solutions in the newly formed crystal lattice during the non-equilibrium growth of the crystal. However, mineral nanoparticles could precipitate directly from the interfacial fluid when it evolves to a supersaturated situation. To better understand the role of mineral nanoparticles in this scenario, this study focuses on a well-documented magnetite with oscillatory zoning from a skarn deposit by using high-resolution transmission electron microscopy (TEM). Our results show that the Al concentration in magnetite measured on a micrometer-scale is caused by three different effects: Al solid solution, Al-rich nanometer-sized lamellae, and zinc spinel nanoparticles in the host magnetite. Here, we propose a genetic relationship among the three different phases mentioned above. At first, a continuous increase of the Al concentration in the interfacial fluid can be incorporated into the crystal lattice of magnetite forming a solid solution. During cooling in a later stage, aluminum in magnetite is oversaturated and exsolution of hercynite (Al-rich lamellae) occurs from the host magnetite. If the Al concentration at the fluid-magnetite interface still increases during further growth of magnetite, the substitution of Fe by Al has gradually reached saturation so that aluminum cannot be incorporated in the magnetite crystal structure any longer. Using the magnetite lattice as a template, nucleation of abundant zinc spinel nanoparticles occurs. This will, in turn, lead to a gradual depletion of Al concentration in the interfacial fluid until the available ions for zinc spinel nucleation and growth have been used up. As a result, the migrating fluid-magnetite interface will enrich the Al concentration in the interfacial fluid until the available ion concentration is sufficient for nucleation of zinc spinel phase again. The fluid-mineral interface in this mechanism has been repeatedly utilized during crystal growth, providing an efficient way for the uptake of trace element from a related undersaturated bulk fluid.

scholarly journals Crystal structures offac-trichloridotris(trimethylphosphane-κP)rhodium(III) monohydrate andfac-trichloridotris(trimethylphosphane-κP)rhodium(III) methanol hemisolvate: rhodium structures that are isotypic with their iridium analogs

2015 ◽  
Vol 71 (2) ◽  
pp. 226-230 ◽  
Author(s):  
Joseph S. Merola ◽  
Marion A. Franks
Keyword(s):  
Crystal Lattice ◽  
Crystal Structures ◽  
Octahedral Coordination ◽  
Distorted Octahedral Coordination ◽  
Distorted Octahedral ◽  
Coordination Spheres

The crystal structures of two solvates offac-trichloridotris(trimethylphosphane-κP)rhodium(III) are reported,i.e.one with water in the crystal lattice,fac-[RhCl3(Me3P)3]·H2O, and one with methanol in the crystal lattice,fac-[RhCl3(Me3P)3]·0.5CH3OH. These rhodium compounds exhibit distorted octahedral coordination spheres at the metal and are isotypic with the analogous iridium compounds previously reported by us [Merolaet al.(2013).Polyhedron,54, 67–73]. Comparison is made between the rhodium and iridium compounds, highlighting their isostructural relationships.

scholarly journals Microstructures and Isothermal Oxidation of the Alumina Scale Forming Nb1.45Si2.7Ti2.25Al3.25Hf0.35 and Nb1.35Si2.3Ti2.3Al3.7Hf0.35 Alloys

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 759 ◽  
Author(s):  
Mohammad Ghadyani ◽  
Claire Utton ◽  
Panos Tsakiropoulos
Keyword(s):  
Solid Solution ◽  
Cast Alloy ◽  
Alumina Scale ◽  
Isothermal Oxidation ◽  
Intermetallic Alloys ◽  
High Entropy ◽  
Heat Treated ◽  
Composite Silicide ◽  
Definition Of ◽  
Selection Of

Coating system(s) will be required for Nb-silicide based alloys. Alumina forming alloys that are chemically compatible with the Nb-silicide based alloy substrate could be components of such systems. The intermetallic alloys Nb1.45Si2.7Ti2.25Al3.25Hf0.35 (MG5) and Nb1.35Si2.3Ti2.3Al3.7Hf0.35 (MG6) were studied in the cast, heat treated and isothermally oxidised conditions at 800 and 1200 °C to find out if they are αAl2O3 scale formers. A (Al/Si)alloy versus Nb/(Ti + Hf)alloy map, which can be considered to be a map for Multi-Principle Element or Complex Concentrated Nb-Ti-Si-Al-Hf alloys, and a [Nb/(Ti + Hf)]Nb5Si3 versus [Nb/(Ti + Hf)]alloy map were constructed making use of the alloy design methodology NICE and data from a previously studied alloy, and were used to select the alloys MG5 and MG6 that were expected (i) not to pest, (ii) to form αAl2O3 scale at 1200 °C, (iii) to have no solid solution, (iv) to form only hexagonal Nb5Si3 and (v) to have microstructures consisting of hexagonal Nb5Si3, Ti5Si3, Ti5Si4, TiSi silicides, and tri-aluminides and Al rich TiAl. Both alloys met the requirements (i) to (v). The alumina scale was able to self-heal at 1200 °C. Liquation in the alloy MG6 at 1200 °C was linked with the formation of a eutectic like structure and the TiAl aluminide in the cast alloy. Key to the oxidation of the alloys was the formation (i) of “composite” silicide grains in which the Nb5Si3 core was surrounded by the Ti5Si4 and TiSi silicides, and (ii) of tri-aluminides with high Al/Si ratio, particularly at 1200 °C and very low Nb/Ti ratio forming in-between the “composite” silicide grains. Both alloys met the “standard definition” of high entropy alloys (HEAs). Compared with HEAs with bcc solid solution and intermetallics, the VEC values of both the alloys were outside the range of reported values. The parameters VEC,  and  of Nb-Ti-Si-Al-Hf coating alloys and non-pesting Nb-silicide based alloys were compared and trends were established. Selection of coating alloys with possible “layered” structures was discussed and alloy compositions were proposed.

Binary niobium alloying with low-melting metals by precipitation of nanoparticles

2019 ◽  
pp. 40-48
Author(s):  
V. N. Volodin ◽  
Yu. Zh. Tuleushev ◽  
S. A. Trebukhov ◽  
A. V. Nitsenko ◽  
N. M. Burabaeva
Keyword(s):  
Solid Solution ◽  
Crystal Lattice ◽  
Liquid State ◽  
Thermal Fluctuation ◽  
The Body ◽  
Lattice Parameters ◽  
Metal Particles ◽  
Lead And Cadmium ◽  
Matrix Lattice ◽  
Melting Effect

Binary niobium alloys with tin, lead and cadmium were obtained by precipitation of nanosized metal particles dispersed in lowpressure plasma using the thermal fluctuation melting effect. The thermal fluctuation melting effect implies that a small particle is in the quasi-liquid state up to a certain critical size which, if exceeded due to steam condensation or fusion (coalescence) of other quasiliquid particles, results in the drop crystallization. The critical sizes of particles being in the quasi-liquid state and capable of coalescing and forming an alloy – solid solution – were found: Nb – 2.1÷2.2 nm, Sn – 0.4 nm, Pb – 0.6 nm, Cd – 3.2 nm. The following concentrations were determined as the boundary of a range where solid metal solutions exist in niobium, at%: Sn – 25.5, Pb – 23.0, Cd – 64.5. The solid solution is a crystal lattice of the niobium as a matrix metal comprising lead, cadmium and tin atoms. The Nb matrix lattice parameters change with additional stresses arising in it up to its destruction due to the fact that the atom sizes of embedded metals differ from those of matrix niobium. The body-centered cubic lattice parameters of solid solutions increase with the rising Pb, Cd и Sn concentrations since they have larger atomic sizes as compared to niobium. A change in the crystal lattice growth rate was observed for lead and cadmium alloys due to a change in the impurity atom arrangement in the niobium matrix lattice. The critical sizes of metal particles obtained were used to estimate surface tension parameters at the crystal/melt interface as follows: 1.17–1.22 J/m2 for Nb, 1.15·10–2 – for Sn; 1.48·10–2 – for Pb; 0.142 – for Cd. Refractory niobium alloying with tin, lead and cadmium is an example of using the size effect to produce new materials.

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