Molten Bi Research Articles

Structural Analysis of Molten Bi–Pb Alloys near Their Liquidus Temperatures

Energy scanning X-ray diffractometry was used for studying the structure of Bi–Pb liquid alloy. All the measurements were made at 10 K above the liquidus temperature. Results were analyzed by defining two kinds of the coordination numbers, Nt and Nm. Both Nm and Nt vary very much at border of eutectic composition. The values of Nm were 6.6 to 7.0 for pure Bi to 44 at% Pb, and 11.0 to 11.2 for 54 at% Pb to pure Pb, and they are very close to the coordination number of primary crystal, respectively, in hypoeutectic and hypereutectic.

Solid-state reaction of Ru and Al in molten Bi

There has been much recent interest in the reactions that occur when two crystalline metals inter-diffuse at low temperatures. Metastable phase formation can occur when structural relaxation into equilibrium crystalline phases is kinetically inhibittedf. These reactions are typically studied in thin—film diffusion couples formed by sequentially depositing two elemental crystalline metals. In this paper we describe a novel low—temperature reaction sequence for the formation of very fine-grain Alx Ru,1-xalloys that allows a further extension of these techniques. This reaction regime uses molten Bi as a medium for the transfer of Al solute atoms to the surface of Ru powder where reaction occurs with the formation Alx Ru1-x,intermetallic phases. The low melting point and ease of handling of Bi, its solvent ability towards Al and Ru, the absence of equilibrium phases of Bi with Al and Ru, and previous experience in our laboratory with equilibrium and metastable phase formation in this system made it attractive as a prototype for this initial study.Ru powder and Al pellets were separatedly prereacted in molten Bi at 500 C for several hours to ensure wetting of the solid surfaces. This Ru and Al and additional excess Bi were then sealed together in a fused silica tube and reacted in a vertical tube furnace. Separate such reactions were carried out at temperatures ranging from 300 to 600 C. After reaction samples were broken free from the fused silica tube and the Bi transfer medium was etched away in concentrated HNO3.

Growth of superconducting single-crystal Bi-Sr-Ca-Cu-O compounds

Three types of Bi-Sr-Ca-Cu-O single crystals with different chemical compositions were grown from molten Bi 2O 3-SrCO 3-CaCO 3-CuO mixtures. Crystals with compositions of Bi 4.4(Sr 3.6Ca 2)Cu 4O z and Bi 4.4 (Sr 4.2Ca 1.4)Cu 4O z exhibit superconductivity with T c's above 80 K. The Bi 4.6(Sr 2.4Ca 1)Cu 2O z crystals, however, do not show superconductivity down to 4.2 K. These crystals have similar structures. Study of composition and X-ray analyses suggested that the ordering of perovskite-like sub-cells has a strong influence on the high- T c superconductivity.

Flow transitions in simulated Czochralski method with tetradecane (C14H30) instead of Bi12SiO20

Flow transitions were observed through the central cross section of the inner flow patterns, using a visualization technique with polyethylene powder. Four flow modes, i.e., stagnant layer, forced convection, core structure and turbulent flow were observed as crystal rotation rate increased. Temperature change in the crucible was largest when the forced convection dominated. Qualitative agreement with a previous result for molten Bi 12 SiO 20 was obtained.

Heat capacity and internal motion of molten Bi+BiI3mixtures

Measurements of the heat capacities, Cp, of molten Bi+BiI3 mixtures at compositions up to around 50 mol.% Bi were made with an adiabatic calorimeter. The deviation Delta Cp,a from the Dulong-Petit law of the atomic heat capacities was calculated over the whole concentration range, including proviously published data for Cp above 50 mol.% Bi. A drastic increase of Delta Cp,a for the ionic liquid-semiconductor regime between around 20 and 50 mol.% Bi (i.e. it has a maximum value of around 2.7R at 50 mol.% Bi) is satisfactorily explained in terms of the internal motions (i.e. the vibrational and rotational modes) of the bismuth homopolyatomic ions, in addition to a contribution from the bismuth iodide complex ions. Between the onset ( approximately 50 mol.% Bi) and the end ( approximately 90 mol.% Bi) of the miscibility gap, Delta Cp,a decreases to less than half of its maximum value. This is because the metallic micro-regions, which are made up of the aggregation of a few of the polybismuth ions or more with the increase of the Bi content, no longer show any internal motion and do not give rise to the large value of Delta Cp,a. Since the molten mixtures between approximately 50 and approximately 90 mol.% Bi are microscopically inhomogeneous solutions consisting of the ionic liquid-semiconducting and metallic micro-regions, the so-called inhomogeneous cluster model is applied to the Delta Cp,a of these mixtures.

Specific heat and TOF neutron diffraction measurements in molten BiBiI 3 mixtures

Heat capacities of molten BiBiI 3 mixtures were determined by means of adiabatic calorimetry. The dependence of the excess heat capacity C p e on the composition was obtained from the observed C p values: the peak of C p e is located at ca. 50 mol% Bi. It is demonstrated that there exists the significant correlation between the dependences of C p e and the first peak distance in the distribution function, which reflects the BiBi distance in the homopolyatomic species of the Bi elements. The homopolyatomic sp units govern the continuous metal-nonmetal transition which takes place over the range of 50 and 80 mol% Bi.

The Magnetic Susceptibility of Molten Bi — BiCl3, In — InCl3, and In — InBr3 Solutions

AbstractMeasurements of the magnetic susceptibility for Bi — BiCl3, In — InCl3, and In — InBr3 systems in the liquid state were made over a wide composition range. Total diamagnetic susceptibilities of molten Bi — BiCl3 system decrease with increasing temperature. On the other hand, little change of the susceptibility was observed against temperature in both molten In systems. Composition dependences of the magnetic susceptibility indicate that apparent paramagnetic contributions exist both in the metal rich and in the salt rich regions of the molten Bi — BiCl3 system, while an extreme electron localization occurs in the composition range between pure salt and 66.7 mol‐% In in the molten In systems. The valency of existing ions and the degree of electron localization are discussed using these experimental results.

Role of grain size in liquid-metal embrittlement of iron

The phenomenon of liquid-metal embrittlement is determined to a significant degree by the structure of the material and the conditions of deformation. It has been experimentally established that with an increase in grain size of pure metals and low-alloy alloys the effect of a liquid-metal medium increases. For alloys a linear relationship has been revealed between the true tensile strength and D -~2 (D is the average grain size). However, the majority of investigations have been made at constant temperature. In studying the change in temperature of the ductile-brittle transformation on samples with different grain sizes [i] a linear relationship of it to log D was obtained. The tests were made on u-brass in mercury, and in th~s case there is a possibility of diffusion penetration of the medium. Therefore, it is of interest to investigate the influence of grain size on the temperature range of embrittlement for systems in which diffusion or corrosion solution is practically absent. Below are given the results of such investigations on Armco iron in molten Bi, Pb, and their eutectic. The greatest~umber of tests was made in Pb--Bi eutectic since as a result of its low melting point tests may be made at lower temperatures. Tension of the 9-mm-diam. cylindrical samples was on a reequipped MP-4G unit at a rate of movement of the clamp of 5%/min. Different grain sizes were obtained b~ appropriate heat treatment of the samples in vacuum: anneal at 1200=C for 5 h for 120 ~m; anneal at II00~ for 2 h for 35 ~m; normalize with subsequent tempering at 500~ for i h for 20 ~m. The samples were covered with a solder of the appropriate low-melting metal in the presence of flux, placed in a vessel with the liquid metal, and tested in a vacuum chamber.

Volcano-shaped relation between heats of oxide formation of metals and coal-liquefaction activities of liquid-metal catalysts

Plots of coal-liquefaction activities of molten Zn, Cd, Ga, In, Tl, Bi, Sn, and Pb against the heats of oxide formation of these metals exhibited a volcano-shaped relationship which suggests that the interactions between the atoms of the catalyst metal and the oxygen atoms which link the structural units of coal are one of the important factors which determine coal-liquefaction activity.

Rebinder effect in the fracture of Armco iron in liquid metals

The aim of the work described in this article was to Investigate the influence of low-melting metal melts on the mechanical properties of Armco iron (0.037% C) specimens in active tension, to find whether the influence of these melts is selective when vacuum is used to protect the solid metal against oxidation, and to formulate certain general laws governing the influence of working media under these conditions. The tests were carried out on solid cylindrical specimens (9 mm diameter) previously annealed by being held for 2 h at II00~ in vacuum (at the residual gas pressure of 6- i0- 3 Pa) to produce an average grain size of 35 ~m. Molten Cd, Ga, Bi, Pb, and Sn and Pb-Bi and Bi-Cd eutectics were used as the working media. The gauge portion of each specimen was pretinned with the aid of a soldering iron under a flux cover. Then the specimen was mounted in a shackle fitted with a vessel containing a given melt. The tests were carried out on a modified type MP-4G [13] machine in a vacuum chamber at the residual pressure of 10 -2 Pa and in the temperature range 200-600~ The traverse rate of the moving shackle was 5%/mhl. This method of testing has the following advantages: It ensures efficient wetling of the specimens during tests even by such �9 ~a as liquid lead and bismuth; the test results are not significantly affected by oxygen and other active constituents of air; and the scatter of experimental data is greatly reduced [14]. The phenomenon of liquid-metal embrittlement (LME) consists in that metal or alloy specimens subjected to the influence of tensile stresses in the presence of molten metals fail by brittle fracture or exhibit lower ductility than those observed in tests in inert working media. At the same time, as was shown in [15], the primary and universal manifestation of the influence of the working medium is a decrease in the resistance of the solid to plastic deformation. On the macroscopic scale this effect is observed at elevated {ernperatures, when stress relaxation plays an important part. Ln cases when relaxation phenomena in a solid under strain are inhibited, adsorption-activ e

硫化水素と溶融金属間の水素発生反応について

Hydrogen as a secondary source of clean energy commands world-wide attention at present, regarding its indefinite supply in the form of water, its storage and transportation characteristic which are both superior to electric power, and its wide metallurgical and chemical usage.The decomposition reaction of H2S to produce H2 and S0for recycle can be regarded as a main step reaction in many closed thermochemical water-splitting cycles based on sulfur chemistry. For this reason, the decomposition of H2S with molten metals was studied.As molten metals, Pb, Sn, and Bi were examined. Experiments were carried out in two ways. One is circulation and bubbling of H2S gas into a molten metal. The other is soft blowing at the surface of the metal bath.Conversion of H2S to H2 with Bi, Pb, and Sn increased in that order. In soft blowing of H2S at the surface of molten metals, the formation of a dense film of the solid sulfide hindered the reaction. Such prevention was not found in the experiment with molten Bi, owing to much larger solubility of S in Bi (1).Generation of H2 was accelerated by the addition of Ni or Cu. This is due to the catalytic action of dissolved Ni or Cu in the melt. Addition of Cu to Pb accelerated the reaction even in the soft blowing of H2S at the surface of molten Pb. It was found that crystal growth of PbS was affected by the presence of Cu and powdery PbS was formed in stead of a dense film. Although the addition of Ni to Sn accelerated the generation of H2 there was a marked tendency to cause strong adhesion of the solid sulfide onto the inner wall of the lance.

Solid Amorphous Bi, Ga, and Fe as Examples of Liquid-Like Amorphous Substances

Experiments show that two structures simultaneously occur in liquid-like solid amorphous and in molten Bi and Ga, i.e., the spherical close packing in the form of a straight atomic chain and the layer lattice structure. In Bi the layer lattices are derived from the respective lattice and in Ga they are remainders of the lattice. In solid amorphous Fe the spherical close packing shows up as a zigzag chain in the atomic distribution curve as in molten Na. Differing from Bi and Ga, in amorphous Fe the layer lattices are parts of the lattice.

Solid Amorphous Bi, Fe, and Ga as Examples of Liquid-Like Amorphous Substances

Solid amorphous Bi, Fe, and Ga are liquid-like, i.e., they have the same structure as the respective melt. However, the degree of order is higher than in the liquid state. A detailed analysis of the structure of liquid-like solid amorphous Bi and Fe (8-coordination) is given. Their atomic distribution curves are compared with those of molten Bi and Na (8-coordination). By discussion of the electron diffraction patterns of solid amorphous and of molten Bi one finds a layer lattice structure (IInd structure) which is derived from the appertaining lattice. The Fourier analysis of the intensity curves, however, demands the spherical close packing in the form of a straight atomic chain (Ist structure). Fujime’s electron diffraction patterns of solid amorphous Fe also show that there exist two structures simultaneously: a layer lattice structure of the appertaining lattice (IInd structure) and the spherical close packing, this time as a plane zigzag chain (Ist structure) as in molten Na. This double structure is also obtained in solid amorphous and in molten Ga. The noncrystalline Ga has an especially simple structure as found immediately by discussion of the intensity curve. In solid amorphous and in molten Bi, Fe, and Ga the simultaneous occurrence of two structures stabilizes the noncrystalline state.

Double structure of molten metals

Abstract Experiments show that two structures occur in solid amorphous and in molten Bi, i.e. the spherical close packing and the layer lattice structure. Here the layer lattices are neither a fragment nor a part of the Bi lattice, but they are produced from the lattice by a reduction of the interlayer distance. This double structure is also found in the monoatomic metal melts. In the atomic distribution curves of molten In and Sn the double structure shows up as a straight atomic chain with the respective distances within the chain rv =v×r 1 and rv/' =v×r 1/', where r 1 and r 1/' mean the shortest atomic distance in the spherical close packing and in the layer lattice structure. In the melts of Au, Ag, Pb and T1 as of Na and Cs, however, the spherical close packing shows up as a zig-zag chain. The straight atomic chain and the zig-zag chain are in fact imaginary, being parts of layer lattices with limited order. In conclusion the real zig-zag chain of solid amorphous Se is considered. Even here layer lat...

Melting and freezing of metals

A method is described for measuring the thermoelectric power of metals in the immediate neighbourhood of their melting points, for both the solid and the molten states, and for thermojunctions formed between them. Results are recorded for the metals Sn, Pb, In, Bi, Cd and Ga. On melting, a jump in thermoelectric power is observed in the negative sense for Pb, In, Cd and Ga and in the positive sense for Bi and Sn. Premelting trends are found in solid In and Cd, and also possible prefreezing effects in molten Sn and Bi.

Electrical Conductivity of Molten Bi–BiCl3 and Bi–BiBr3 Solutions

The electrical conductivities of molten Bi–BiBr3 solutions were measured as a function of temperature over the entire composition range; the conductivities of Bi–BiCl3 solutions were measured from pure salt to 30 mole % metal. In general, these two systems are very similar. Above 400°C, they resemble the Bi–BiI3 system in which conductivity increases monotonically with metal content; but below 300°C in salt-rich solutions, the conductivities of these two systems decrease with increasing metal content. Between 10 and 80 mole % Bi in the Bi–BiBr3 system and between 10–30 mole % Bi in the Bi–BiCl3 system, positive temperature coefficients were found at all temperatures. Above 500°C, the three predominating conductivity mechanisms are believed to be ionic at less than 10% metal, semiconducting between 20% and 60% metal, and metallic above 80% metal.

The Use of α‐Spectroscopy for Studying Anodic Oxidation

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Magnetic Susceptibilities of Molten Bi–BiI3 Solutions

Magnetic susceptibility measurements were made with a Gouy balance on molten Bi–BiI3 solutions at 450°–600°C over the entire composition range. The susceptibilities were diamagnetic throughout and were found to become less diamagnetic as temperature increased. This temperature dependence varied with concentration of bismuth and was greatest in the 30–70 mole % Bi solutions. The molar susceptibility as a function of mole fraction of bismuth showed slight deviations from simple additivity in a diamagnetic direction in the salt-rich region and larger deviations from additivity in a paramagnetic direction in the metal-rich melts. This magnetic behavior is discussed in terms of possible chemical species as well as the free-electron model.

SPECTRA OF DILUTE SOLUTIONS OF BISMUTH METAL IN MOLTEN BISMUTH TRIHALIDES. I. EVIDENCE FOR TWO SOLUTE SPECIES IN THE SYSTEM BISMUTH—BISMUTH TRICHLORIDE1

Solute bismuth metal in chloride-rich melts of the system Bi--BiCl3 was found to be partitioned into two chemical species which obey the law of additive absorbances. Absorption spectra from 450 to 750 m mu are reported for molten Bi--BiCl3 mixtures 0.0027 to 0.7 M in solute bismuth metal at path lengths as short as 24 mu and at temperatures of 264, 350, and 433 deg . The spectrum consists of an intense, broad band with a maximum near 560 m mu . Large apparent deviations from Beer's law were found at all wave lengths. TMese spectra had the characteristics expected for solutions with two light-absorbing solute species. Phenomenological equations were derived which describe the spectra of solutions consisting of any given number of solute species derived from a common substance.

Removal of the More Noble Nonvolatile Fission Products from Uranium-Bismuth Fuels

The liquid-metal-fuel reactor concept in its commonest version is a thermal breeder and employs as a fuel a dilute solution of U in molten Bi. About 28% of the nonvolatile fission products are less reactive chemically than U. This FPN group is further divided into three subgroups according to the proposed methods of removal. The FPN-I's would be removed by oxidizing them to chlorides with fused salts, the FPN-II's by precipitating them directly from the liquid fuel, and the FPN-III's by reaction with Zn to form low-density intermetallic compounds which are insoluble in Bi. The FPN-II's, representing about 90% of the FPN's, would be removed continuously, while the others, because of their low yields or relatively low thermal cross sections, would be allowed to build up in the fuel for several years without causing any particular concern. The FPN-I's would be removed by the same continuous process proposed for removing those nonvolatile fission products which are more reactive than U, while the FPN-III's would be removed in a batch process similar to that used in the refining of Bi. Information is included on the rates of more » build-up of FPN elements in the fuel, steady-state concentrations of the FPN-II elements, reactor poisoning level of the FPN's, and experimental results in support of the proposed methods of removal. (auth) « less