scholarly journals Influence of Liquid Quenching on Phase Composition and Properties of Be-Si Eutectic Alloy

2020 ◽  
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Eutectic Alloy ◽  
Electrical Resistance ◽  
Liquid State ◽  
Foil Thickness ◽  
Continuous Heating ◽  
Cooling Rates ◽  
Liquid Quenching ◽  
Substitutional Solid Solutions

By the method of quenching from the liquid state (splat-quenching), it is first revealed the formation of mixture of metastable supersaturated substitutional solid solutions in the eutectic alloy Be-33at.% Si. Cast samples are obtained by pouring melt into a copper mold. High cooling rates during liquid quenching are achieved throw the well-known splat-cooling technique by spreading a drop of melt on the inner surface of a rapidly rotating, heat-conducting copper cylinder. The maximum cooling rates are estimated by the foil thickness. The melt cooling rates (up to 108К/s), used in the work, are sufficient to form amorphous phases in some eutectic alloys with similar phase diagrams, but it is found those rates are insufficient to obtain them in the Be-Si eutectic alloy. The X-ray diffraction analysis is carried out on a diffractometer in filtered Cobalt Ka radiation. Microhardness is measured on a micro-durometer at a load of 50 g. The electrical properties, namely the temperature dependences of relative electrical resistance, are studied by the traditional 4-probe method of heating in vacuum. The accuracy of determining the crystal lattice period of the alloy, taking into account extrapolation of the reflection angle by 900, is ± 3•10-4 nm. It is found that even at extremely high rate of quenching from the melt, instead of the amorphous phase formation, the occurrence of two supersaturated substitutional solid solutions, based on Beryllium and Silicon, is revealed. This fact is established by the obtained dependences of their lattice periods values on the alloying element content. So, during the formation of metastable eutectic structure, a supersaturated with Beryllium solid solution of Silicon has period a = 0.5416 nm, and a supersaturated with Silicon solid solution of low-temperature hexagonal Beryllium has periods a = 0.2298 nm, c = 0.3631 nm. The positive role of the liquid quenching method in increasing the level of mechanical characteristics (microhardness and microstresses) in rapidly cooled Be-Si films is shown. It has been demonstrated that the difference in the atomic radii of the elements significantly affects the distortion of crystal lattices of the formed supersaturated solid solutions, and a significant value of microstresses (second-order stresses) in the Silicon lattice supersaturated with Beryllium is estimated, which, of course, leads to a significant increase in the microhardness, namely: there is an increase in microhardness in the Be-Si alloy under the conditions of applied method of quenching from the liquid state by more than 1.7 times compared to cast eutectic alloy and more than 6 times higher in comparison with the eutectoid cast Iron-Carbon alloy. The obtained polytherm of electrical resistance of the alloy under conditions of continuous heating in vacuum confirms the metastable nature of obtained new phases during quenching from the liquid state.

The Electrical Resistance of Dilute Solid Solutions

1936 ◽  
Vol 32 (2) ◽  
pp. 281-290 ◽  
Author(s):  
N. F. Mott
Keyword(s):  
Solid Solution ◽  
Electrical Conductivity ◽  
Solid Solutions ◽  
Electrical Resistance ◽  
Unit Volume ◽  
Effective Number ◽  
Free Electrons ◽  
Mechanical Explanation ◽  
Image Position ◽  
Matthiessen's Rule

1. As is well known, the electrical resistance of a metal is very greatly in-creased by the addition of a second metal with which it forms a solid solution. The increase Δρ in the resistivity due to the addition of a small percentage of the second metal is in general independent of the temperature (Matthiessen's rule), though there are oertain exceptions (e.g. Cr in Au). The quaritum-mechanical explanation of both these facts was first given by Nordheim, and may be expressed as follows: the electrical conductivity of any metal may be written in the formwhere τ is the “time of relaxation”, equal to half the time between collisions, and N is the effective number of free electrons per unit volume: hence, for the resistivity, we have

scholarly journals Diffusionless (chemically partitionless) crystallization and subsequent decomposition of supersaturated solid solutions in Sn–Bi eutectic alloy

2019 ◽  
Vol 377 (2143) ◽  
pp. 20180204 ◽  
Author(s):  
Olga V. Gusakova ◽  
Peter K. Galenko ◽  
Vasiliy G. Shepelevich ◽  
Dmitri V. Alexandrov ◽  
Markus Rettenmayr
Keyword(s):  
Solid Solution ◽  
Eutectic Alloy ◽  
Supersaturated Solid Solution ◽  
Eutectic Growth ◽  
Rapid Quenching ◽  
Cooling Rates ◽  
Internal Structures ◽  
Supersaturated Solid Solutions ◽  
Rapidly Solidified ◽  
Subsequent Decomposition

Results of a study on microstructural evolution of eutectic Sn-57 wt.% Bi processed with cooling rates of 10 −2 , 1 K s −1 and approximately 10 5  K s −1 are presented. In order to distinguish different mechanisms of microstructure formation, a comparison with microstructures of different hypoeutectic alloys with compositions down to below the maximum solubility of Bi in Sn–Bi is undertaken. It is found that at the cooling rates of 10 −2 and 1 K s −1 , coupled eutectic growth occurs, leading to lamellar structures with different length scales. At the rapid quenching rates of approximately 10 5  K s −1 , structure formation in the eutectic alloy is qualitatively different. Partitionless solidification resulting in a supersaturated solid solution with the initial composition is observed in both eutectic and hypoeutectic alloys. It is shown that the observed microstructure of the rapidly solidified alloys forms by the decomposition of the supersaturated solid solution. This article is part of the theme issue ‘Heterogeneous materials: metastable and non-ergodic internal structures’.

scholarly journals The structure of rapidly solidified foil of the eutectic Sn – 8.8 wt. % Zn alloy

2020 ◽  
pp. 67-72
Author(s):  
Vasili G. Shepelevich ◽  
Denis A. Zernitsa
Keyword(s):  
Solid Solution ◽  
Specific Surface ◽  
Solid Solutions ◽  
Eutectic Alloy ◽  
Volume Fraction ◽  
Average Particle Size ◽  
Unstable State ◽  
Average Particle ◽  
Alloy Foil ◽  
Rapidly Solidified

Microstructure of rapidly solidified eutectic alloy foil Sn – 8.8 wt. % Zn was studied. The alloy foil consists of solid solutions of zinc and tin. Dark equiaxed dispersed precipitates of zinc solid solution are uniformly interspersed in the matrix of tin solid solution. The parameters of the microstructure were determined. The average chord of a random secant at the sections of precipitates of a solid solution of zinc is 0.33 mm, and the specific interface surface is 0.81 mm–1. The precipitations of the tin solid solution have a microcrystalline structure. Specific surface of high angle boundaries less than 1 mm–1. The texture of the precipitates of solid solutions of tin and zinc in the foil was studied, and the pole densities of the diffraction lines of these phases are presented. The tin solid solution has the texture (100), and the zinc solid solution has the (0001) texture, which is explained by the predominant growth of grains, in which the crystalline planes of (100) tin and (0001) zinc are most closely packed and perpendicular to the heat flux. Eutectic alloy Sn – 8.8 wt. % Zn is in an unstable state. Annealing the foil causes the dissolution of small and coarsening of large particles of zinc solid solution, as well as the decomposition of a supersaturated tin solid solution. These processes cause an enlargement of the microstructure: an increase in the average particle size (dZn) of a solid solution of zinc and its volume fraction (VZn), a decrease in the specific surface (S ) of interphase boundaries.

Phonon Spectrum of Crystals InxTl1 – xI Substitutional Solid Solutions

2016 ◽  
Vol 8 (1) ◽  
pp. 01010-1-01010-5 ◽  
Author(s):  
A. I. Kashuba ◽  
◽  
S. V. Apunevych ◽  
Keyword(s):  
Solid Solutions ◽  
Phonon Spectrum ◽  
Substitutional Solid Solutions

scholarly journals Synthesis of Ce1−xPdxO2−δ Solid Solution in Molten Nitrate

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 640
Author(s):  
Hideaki Sasaki ◽  
Keisuke Sakamoto ◽  
Masami Mori ◽  
Tatsuaki Sakamoto
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Ionic States

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

Electron microprobe study of turquoise-group solid solutions in the Neyshabour and Meydook mines, northeast and southern Iran

2020 ◽  
Vol 58 (1) ◽  
pp. 71-83
Author(s):  
Elahe Mansouri Gandomani ◽  
Nematollah Rashidnejad-Omran ◽  
Amir Emamjomeh ◽  
Pietro Vignola ◽  
Tahereh Hashemzadeh
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Electron Microprobe ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Major Elements ◽  
Point Of View ◽  
Chemical Compositions ◽  
Light Blue ◽  
Quaternary Solid Solution

ABSTRACT Turquoise, CuAl6(PO4)4(OH)8·4H2O, belongs to the turquoise group, which consists of turquoise, chalcosiderite, aheylite, faustite, planerite, and UM1981-32-PO:FeH. In order to study turquoise-group solid solutions in samples from the Neyshabour and Meydook mines, 17 samples were selected and investigated using electron probe microanalysis. In addition, their major elements were compared in order to evaluate the feasibility of distinguishing the provenance of Persian turquoises. The electron microprobe data show that the studied samples are not constituted of pure turquoise (or any other pure endmember) and belong, from the chemical point of view, to turquoise-group solid solutions. In a turquoise–planerite–chalcosiderite–unknown mineral quaternary solid solution diagram, the chemical compositions of the analyzed samples lie along the turquoise–planerite line with minor involvement of chalcosiderite and the unknown mineral. Among light blue samples with varying hues and saturations from both studied areas, planerite is more abundant among samples from Meydook compared with samples from Neyshabour. Nevertheless, not all the light blue samples are planerite. This study demonstrates that distinguishing the deposit of origin for isochromatic blue and green turquoises, based on electron probe microanalysis method and constitutive major elements, is not possible.

Epitaxial Solid-Solution Films of Immiscible MgO and CaO

1994 ◽  
Vol 341 ◽  
Author(s):  
E. S. Hellman ◽  
E. H. Hartford
Keyword(s):  
Solid Solution ◽  
Molecular Beam Epitaxy ◽  
Lattice Constant ◽  
Solid Solutions ◽  
Molecular Beam ◽  
Building Blocks ◽  
Layer Growth ◽  
Growth Mode ◽  
Miscibility Gap ◽  
Layer By Layer

AbstractMetastable solid-solutions in the MgO-CaO system grow readily on MgO at 300°C by molecular beam epitaxy. We observe RHEED oscillations indicating a layer-by-layer growth mode; in-plane orientation can be described by the Matthews theory of island rotations. Although some films start to unmix at 500°C, others have been observed to be stable up to 900°C. The Mgl-xCaxO solid solutions grow despite a larger miscibility gap in this system than in any system for which epitaxial solid solutions have been grown. We describe attempts to use these materials as adjustable-lattice constant epitaxial building blocks

Cationic Substitutions in Sphalerite from the Porgera Mine, Papua New Guinea

2021 ◽  
Author(s):  
Christopher H. Ingles ◽  
John A. Mavrogenes
Keyword(s):  
Solid Solution ◽  
Papua New Guinea ◽  
Solid Solutions ◽  
Inductively Coupled Plasma ◽  
New Guinea ◽  
Inductively Coupled ◽  
Cationic Substitution ◽  
Plasma Mass Spectrometry ◽  
Positive Correlations

ABSTRACT Laser ablation-inductively coupled plasma-mass spectrometry was used to traverse hydrothermal vein sphalerite from different ore-forming stages of the Porgera Au-Ag mine, Papua New Guinea. Elements were measured in situ over the growth of crystals to investigate the greatly varying concentrations of cations in sphalerite and their positions in the lattice. Traverse profiles for 16 elements were obtained and aligned to transmitted light images where possible. Each sample contained an array of elements, with many displaying orders of magnitude concentration differences. Results show the simultaneous incorporation of Cu and Sn in sphalerite, as well as Cu and Ag, In and Sn, As and Sb, Fe and Mn, and Cu and Ga. The relation [4Zn2+ ↔ 2Cu+ + Sn2+ + Sn4+] is proposed to explain the 1:1 Cu–Sn correlation. Further relations can be seen, including a Ga “ceiling” or Cu “floor”, where Ga incorporation becomes dependent on Cu concentrations. Furthermore, silver was also observed to correlate with Au, Mn, Ni, Pb, and Bi. Meta-stable solid solutions between pairs such as Cu, Ag; Fe, Mn; As, Sb; and In, Sn are also suggested. Each of these pairs are neighbors on the periodic table of elements, which suggests that simple solid solution can occur, and positive correlations for all four solid solutions were found in one sample alone. While the concept of charge-specific solid solutions in sphalerite has been discussed in the literature with reference to monovalent cations, the results presented herein also indicate solid solutions of higher oxidation states, containing many cations. Furthermore, while cations in charge-specific solid solutions have been proposed to compete for lattice sites in sphalerite, simultaneous in situ coupled concentrations at Porgera suggest otherwise. Cationic substitution equations displaying decimal ratios of each element in solid solution can then provide a novel method to distinguish between solid solution concentrations in different samples. For example, displaying 1:1 ratios of Cu–Ag and Sb–As: [2Zn2+ ↔ (Cu+0.5, Ag+0.5) + (As3+0.5, Sb3+0.5)], or for a 100:1 Fe–Mn ratio: [Zn2+ ↔ (Fe2+0.99, Mn2+0.01)].

Neutron Diffraction Studies on the Structure and Conduction Mechanism in Al, Ga—DOPED Li4SiO4

1990 ◽  
Vol 210 ◽  
Author(s):  
R.I. Smith ◽  
A.R. West
Keyword(s):  
Solid Solution ◽  
Neutron Diffraction ◽  
Solid Solutions ◽  
Conduction Mechanism ◽  
One Dimensional ◽  
Linear Defects ◽  
Solution Mechanism

AbstractCrystallographic results on the Li4-3x(Al,Ga)xSiO4 solid solutions are reviewed. The six sets of sites available for Li+ ions fall into two groups. The ‘framework’ sites, which also contain the substitutional Al,Ga ions, appear to have little effect on conductivity. The ‘channel’sites contain varying amounts of Li+ ions and are responsible for the dramatic variations in conductivity with x. There is evidence for the presence of one—dimensional defects, comprising columns of ordered Li+ ions, in both the framework and channel sites. The relative numbers of these linear defects has a large bearing on the solid solution mechanism in the framework sites and their occurrence in the channel sites may be responsible for the low conductivity in stoichiometric Li4SiO4.

Synthesis of ZrO2–Y6WO12 solid solution powders by a polymerized complex method

1998 ◽  
Vol 13 (4) ◽  
pp. 939-943 ◽  
Author(s):  
Junfeng Ma ◽  
Masahiro Yoshimura ◽  
Masato Kakihana ◽  
Masatomo Yashima
Keyword(s):  
Solid Solution ◽  
Crystallite Size ◽  
Surface Area ◽  
Solid Solutions ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Complex Method ◽  
Amorphous Precursor ◽  
Fine Powders ◽  
Polymerized Complex Method

A series of solid solutions (1 − x) ZrO2 · xY0.857 W0.143 O1.714 (1/7Y6WO12) of metastable cubic phase were synthesized at 800 °C through a polymerized complex method. Lattice parameter a0 of solid solutions varies linearly with Y0.857 W0.143 O1.714 content (x). Crystallization began to occur above 400 °C from amorphous precursor to yield at 800 °C fine powders of 6–10 nm and 19–40 m2/g for crystallite size and surface area, respectively.

Sign in / Sign up

Export Citation Format

Share Document