Interactions in the LiPO3 — MoO3, NaPO3 — MoO3, and KPO3 — MoO3 systems

The MPO₃ — MoO₃ (M=Li, Na, K) pseudobinary systems have been examined by differential thermal analysis and x-ray phase analysis. The phase diagrams have been derived, and the temperatures and compositions of the eutectics have been determined. The compounds have been examined by x-ray phase analysis, infrared spectroscopy, and diffuse reflection spectroscopy. The conductivity and optical properties of the compounds MMoO₂(PO₄) (M=Li, Na, K) have been determined. The coordinates of the liquidus lines have been used to calculate the activities of the components in the MPO₃ — MoO₃ systems. Those activities show large negative deviations from ideal solutions. This indicates strong interaction between particles in the liquid state. Translated from Poroshkovaya Metallurgiya, Nos. 3–4(412), pp. 33–40, March–April, 2000.     

Bulk amorphous metallic alloys: Synthesis by fluxing techniques and properties

Bulk amorphous alloys having dimensions of at least 1 cm in diameter have been prepared in the Pd-Ni-P, Pd-Cu-P, Pd-Cu-Ni-P, and Pd-Ni-Fe-P systems using a fluxing and water-quenching technique. The compositions for bulk glass formation have been determined in these systems. For these bulk metallic glasses, the difference between the crystallization temperature (T _x) and the glass transition temperature (T _g, ΔT=T _x−T _g) ranges from 60 to 110 K. These large values of ΔT open the possibility for the fabrication of amorphous near-net-shaped components using techniques such as injection molding. The thermal, elastic, and magnetic properties of these alloys have been studied, and we have found that bulk amorphous Pd₄₀Ni_22.5Fe_17.5P₂₀ has spin glass behavior for temperatures below 30 K. This article is based on a presentation made in the “Structure and Properties of Bulk Amorphous Alloys” Symposium as part of the 1997 Annual Meeting of TMS at Orlando, Florida, February 10–11, 1997, under the auspices of the TMS-EMPMD/SMD Alloy Phases and MDMD Solidification Committees, the ASM-MSD Thermodynamics and Phase Equilibria, and Atomic Transport Committees, and sponsorship by the Lawrence Livermore National Laboratory and the Los Alamos National Laboratory.     

High-temperature constructional powder steel and alloys

Strong new alloys based on intermetallic Fe-Cr-Al compounds and systems with strengthening by refractory nanoparticles may be used in heat-stressed components of high-speed airplanes and jet engines and in heat exchangers for the oil and atomic industries. Experiments confirm the high performance of such dispersely hardened materials. The small-scale production of hot-deformed components from dispersely hardened high-temperature ferritic ПX25Ю6 + 0.5% Y₂O₃ steel has been introduced.     

Thermodynamic study of liquid Cu-Mg alloys by vapor pressure measurements

Thermodynamic properties of liquid Cu-Mg alloys have been determined by magnesium vapor pressure measurements over pure liquid magnesium and liquid Cu-Mg alloys, in the composition range of 11 to 90 mole pct Mg between 845 and 1345 K, employing the transpiration technique. Based on the quadratic formalism suggested by Turkdogen and Darken for binary systems, analytical expressions have been derived representing integral and partial molar thermodynamic properties as functions of composition for the two terminal regions of suN Mg = 0 to 0.33 and 0.6 to 1.0. From the measured activity values of magnesium and copper, in the liquid alloys in equilibrium with solid intermetallic compounds, standard free energies of formation of Cu₂Mg(s) and CuMg₂(s) relative to pure solid components have been calculated and expressed as functions of temperature. Extractive Metallurgy Section, Metallurgy Division     

Calculation of sulfide capacities of multicomponent slags

The Reddy-Blander model for the sulfide capacities of slags has been modified for the case of acid slags and to include A1₂O₃ and TiO₂ as components. The model has been extended to calculatea priori sulfide capacities of multicomponent slags, from a knowledge of the thermodynamic activities of the component oxides, with no adjustable parameters. Agreement with measurements is obtained within experimental uncertainty for binary, ternary, and quinary slags involving the components SiO₂-Al₂O₃-TiO₂-CaO-MgO-FeO-MnO over wide ranges of composition. The oxide activities used in the computations are calculated from a database of model parameters obtained by optimizing thermodynamic and phase equilibrium data for oxide systems. Sulfur has now been included in this database. A computing system with automatic access to this and other databases has been developed to permit the calculation of the sulfur content of slags in multicomponent slag/metal/gas/solid equilibria. Formerly Graduate Student with the Centre for Research in Computational Thermochemistry, Ecole Polytechnique.     

A model for wear-resistant coating on aluminum alloy formed by spark mass transfer of a composite ceramic

Measurements have been made on the mass-transfer kinetics, structure, and properties of the surface layer in spark mass transfer of composite ceramics in the systems AlN-Ti(Zr)B₂ and LaB₆-ZrB₂. A model is proposed for the formation of the wear-resistant coating on aluminum alloys, which is based on the screening action of the vapors and particles of the nonconducting phases in the electrode gap and involves the differing wettability of the alloying components by the substrate material. __________ Translated from Poroshkovaya Metallurgiya, Nos. 1–2(447), pp. 51–58, January–February, 2006.     

Physico-Chemical Computer Simulation of Arsenic Compounds Precipitation from Chloride Solutions

The purpose of the present investigation was to examine solubilities of arsenic compounds and to determine parameters of arsenic selective precipitation from chloride solutions of complicated composition. The following arsenic-containing systems were examined.

MCl_m-HCl-CaCl₂-H₂S-H₂O precipitation of As₂S₃

MCl_m-HCl-CaCl₂-SnCl₂-H₂O precipitation of As

MCl_m-HCl-CaCl₂-Ca(OH)₂,CaCO₃-H₂O precipitation of M_m(AsO₃) _n

M = As, Sn, In, Pb, Bi, and Fe (metals present in solutions simultaneously). The free energy minimization method has been applied to determine an equilibrium composition of liquid, solid, and gaseous phases of multicomponent systems. The computations have been performed according to the program-package SELECTOR. Thermodynamic data for a number of Sn, Pb, In, and As sulfides, Chlorides and hydroxides, required for computations were obtained or precised by solving the so-called inverse problem; thermodynamic properties were computed on the basis of experimental solubility data for simple systems. The obtained thermodynamic data have been used in simulating industrial hydrometallurgical processes.

Physico-chemical simulation resulted in determination of equilibrium phase composition of multisystems and the composition of each phase. It revealed the effect of hydrochloric acid, metals, chloride-ions concentrations as well as gaseous components partial pressure and temperature on solubility of As, Sn, In, Pb, Bi, and Fe compounds. In particular, the solubilities and stabilities of metal arsenates, chlorides, sulfides, carbonates, hydroxides, and oxides were predicted. Model analysis also made it possible to obtain quantitative characteristics on metals and arsenic speciation in aqueous solutions depending on pH. Eh, and chloride ion concentration. Parameters providing selective arsenic removal from chloride solutions comprising tin, lead, indium, and some other metals were determined with high extent of reliability.     

Phase diagram of the Al2O3 - ZrO2 - Nd2O3 system. III. Solidus surface and phase equilibria in alloy crystallization

A projection has been constructed for the solidus surface in the Al₂O₃ - ZrO₂ - Nd₂O₃ phase diagram on the plane of the concentration triangle, which consists of six isothermal three-phase fields corresponding to two nonvariant equilibria of eutectic type and four nonvariant ones of peritectic type, together with five lineated surfaces for the end of crystallization of the monovariant eutectics. The highest solidus temperature in the system is 2710°C, the melting point of pure ZrO₂ , and the least is 1675°C, the temperature of the ternary eutectic L ? β + F + NA. No ternary phases and no appreciable regions of solid solutions based on their components and the binary compounds have been observed. Data on the adjoining binary systems, liquidus and solidus surfaces allowed for construction of the phase equilibrium diagram together with a reaction scheme for the equilibrium crystallization of alloys in the Al₂O₃ - ZrO₂ - Nd₂O₃ system.     

RECENT DEVELOPMENTS IN THE FIELD OF SILICIDES AND BORIDES OF THE HIGH-MELTING-POINT TRANSITION METALS

Abstract

The binary systems of silicides of the high-melting-point transition metals are now well understood, except for the hafnium-silicon system. Research since 1954 is reviewed, with particular reference to the compound Me₅Si₃ and its position in the silicide systems. Reference is also made to the pseudo-binary and pseudo-ternary silicide systems.

The structures of many of the intermetallic phases in the binary boride systems have now been determined, but complete equilibrium diagrams still remain to be established in some cases. New tentative diagrams are given for the systems vanadium–boron, niobium–boron, and tantalum–boron, and structures are suggested for the borides V₃B₂, Nb₃B₂, and Ta₃B₂ with the T2 structure (isostructural with U₃Si₂).

Ternary alloys of the systems Me–Si–B are of great interest, not only structurally but also for practical reasons. The complete systems Me–Si–B of Group VI (Mo–Si–B and W–Si–B) have accordingly been studied by X-ray, thermal-analysis, and micrographic methods. The system Cr–Si–B has been determined and attention is directed to the possible commercial applications of certain alloys containing additions of metals of the iron group, in particular nickel, for sprayed coatings resistant to liquid aluminium.

The question of cementing silicides and borides with metals and alloys is discussed theoretically. The character of the silicide or boride system in question and the behaviour of the intermediate phase in relation to the bonding material are of decisive importance for the selection of the latter. Only very limited data are to be found in the literature on the behaviour of silicides and borides in relation to metals and alloys. Alloys based on TiB₂, ZrB₂, MoSi₂, and WSi₂, impregnated with numerous metals and alloys, have been prepared. Their structures have been studied and the technical suitability of various combinations is discussed on the basis of their technological properties.     

A Chemical Approach of the Molecular Entity Vacancy Model to the CaO‐Al2O3‐SiO2 Ternary Silicate Melt

A chemical approach of the molecular entity vacancy model (MEVM) to the CaO‐Al₂O₃‐SiO₂ ternary silicate melts has been suggested. The activities of all components in the melts were simultaneously predicted by using only the binary parameters of its sub‐binary melts which were determined by fitting the activities of their two components. The results indicated that the predicted values of activity of SiO₂ were in good agreement with the experimental data at both temperatures 1823 K and 1873 K, and those of CaO and Al₂O₃ were in reasonable agreement with the experimental data at 1823 K and were smaller than the graphical integration data of the Gibbs‐Duhem equation at 1873 K. The approach may be extended to some solution systems with the chemical interaction.     

Activity measurement of the constituents in liquid Cu-Mg and Cu-Ca alloys with mass spectrometry

A mass spectrometer has been used to study activities of the constituents in liquid Cu-Mg and Cu-Ca alloys. Activities and heats of mixing have been determined from a series of measurements of the ratios of the ion current intensity of the solution components according to the Belton-Fruehan treatment. The activities in both systems exhibit negative deviation from ideality and tend to approach an ideal behavior at higher temperatures. The terms of RT ln γ _Cu and RT ln γ _Mg show very small temperature dependence within the present experimental range and agree well with the values reported by Garg et al. for the Cu-Mg system. The terms of RT ln γ _Ca and RT ln γ _Cu are independent of temperature and in excellent agreement with the values assessed by Risold et al. for the Cu-Ca system. Relative partial molar enthalpy and integral heat of mixing in the liquid Cu-Mg and Cu-Ca systems were also estimated. This article is based on a presentation made in the “Geoffrey Belton Memorial Symposium,” held in January 2000, in Sydney, Australia, under the joint sponsorship of ISS and TMS.     

Interaction of silver and phosphorus with zirconium, niobium, and molybdenum

Interaction of components in the systems (Zr, Nb, Mo)−Ag−P is studied by X-ray analysis and phase diagrams are constructed at different temperatures for various phosphorus contents. Ternary compounds are not found in the systems studied. In the Zr−Ag−P system silver dissolves in phosphide Zr₁₄P₉ up to the limiting composition Zr_10.8Ag_3.2P₉. Comparative analysis is performed for interaction of components in (Zr, Nb, Mo)−(Cu, Ag)−P systems. L'vov State University. Translated from Poroshkovaya Metallurgiya, Nos. 1–2(405), pp. 36–39, January–February, 1999.     

Thermodynamic behaviour of carbon in CaO-SiO2 slag system

In order to understand the thermodynamic behaviour of carbon in steelmaking slag at high temperature, the carbon dissolution into CaO-SiO₂ slag system has been investigated including the effects of temperature and slag components on the carbon dissolution reaction. It was found that carbide solubility in the CaO-SiO₂ slag decreased with increasing oxygen potential to confirm the theoretical relationship of ?1/2, which reflected the ionic exchange reaction mechanism between carbon and oxygen ions. Carbide solubility in slag as a function of slag basicity for various slag systems appeared to confirm this mechanism. This reaction mechanism implied that the carbide dissolution proceeded due to the reaction of solid carbon and oxygen ions supplied from (CaO) in slag. The oxygen ion appears to be the driving force as it is influenced by the slag components as well as the temperature as shown in the concept of the carbide capacity of slag. The solubility of carbide in the CaO-SiO₂ slag increased with the addition of CaF₂; the role of CaF₂ for carbide dissolution into slag could be speculated to have complex effects on indirect increase in basicity in spite of (CaO) dilution. Substitution of CaO by MgO decreased the solubility of carbide in the CaO-SiO₂-MgO slag, possibly caused by the relatively low electro-negativity of MgO.     

A Review of Recent Studies on Copper Smelting

Abstract

A review of more important studies on Cu smelting which have appeared in the literature since 1950. The works reviewed comprise studies of the physicochem. systems pertaining to the smelting and converting operations and accounts of recent advances in technology.

The essential physicochem components are Cu, Fe, O, S and SiO₂, and a considerable body of knowledge has accumulated of 2-, 3- and 4-component systems involved in slag;matte equilibria. The distribution of Cu between the 2 liquid phases is strongly influenced by the O potential and silica activity. Much less attention has been given to the kinetic aspects of-cop.per smelting, namely the rates of chem. reactions and of heat and mass transfer; the importance of these phenomena in relation to Cu losses is discussed.     

Phase diagram of the Al2O3-ZrO2-Er2O3 system. I. Isothermal sections at 1250 and 1650°C

Isothermal sections at 1250 and 1650 °C have been constructed for the Al₂O₃-ZrO₂-Er₂O₃ phase diagram. Phase equilibria at these temperatures have been identified. It is not found that there are any ternary compounds or noticeable regions of solid solutions based on the components or binary compounds. Conditionally quasibinary sections have been identified: Er₃A₅-F, ErA-F, and Er₂A-F, which triangulate the Al₂O₃-ZrO₂-Er₂O₃ ternary system.     

Phase diagram of the Al2O3-ZrO2-Sm2O3 system. III. Solidus surface and phase equilibria in alloy crystallization

A projection has been constructed for the solidus surface in the Al₂O₃-ZrO₂-Sm₂O₃ phase diagram on the plane of the concentration triangle, which consists of seven isothermal three-phase fields corresponding to two nonvariant equilibria of eutectic type and five nonvariant equilibria of peritectic type, and also eight lineated surfaces for the end of crystallization of the binary eutectics. The highest temperature on the solidus surface is 2710°C, the melting point of pure ZrO₂, while the lowest is 1680°C, the temperature of the triple eutectic Al + F + SA. No ternary phases or appreciable regions of solid solutions based on the components and the binary compounds are observed. Data on the bounding binary systems, the liquidus and solidus surfaces have been used to construct the phase-equilibrium (melting) diagram together with a reaction scheme for the equilibrium crystallization of alloys in the Al₂O₃-ZrO₂-Sm₂O₃ system. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 56–64, May–June, 2006.     

Derivation of the stress states for (111) (112) multiple slip and twinning

The yield equation of a slip or twinning system is represented by a surface in five dimensional stress coordinates. Because of crystallographic symmetry, the yield surfaces of the twelve {111}〈112〉 twin systems can be arranged as faces of three separate tetrahedra in three-dimensional shear stress coordinates σ₂₃, σ₃₁, σ₁₂. The other two stress components then determine the size of the tetrahedra. For {111}〈112〉 (or {112}〈111〉) slip, three additional tetrahedra are needed for slip in the reverse direction. A general shape change requirement of five or more active twin (or slip) systems may be found as intersections of five or more faces among the tetrahedra with the requirement that the stresses at the intersections do not exceed the yield value for the nonactive systems. These intersections have been obtained systematically. It is verified that the lists of stress states previously reported by Hosford and Chin for {111}〈112〉 multiple slip and twinning are complete.     

Phase Diagram of the Al2O3—ZrO2—Nd2O3 System. Part 1. Isothermal Sections of the Phase Diagram at 1250 and 1650°C

Isothermal sections at 1250 and 1650°C have been constructed for the Al₂O₃—ZrO₂—Nd₂O₃ phase diagram, and the phase equilibria at those temperatures have been identified. No ternary compounds are found, and nor are there appreciable solid-solution ranges based on the components or binary compounds. Partially quasibinary sections have been observed: NdAlO₃—(66.7 mole% ZrO₂—33.3 mole% Nd₂O₃), AL—F, and β—F, which triangulate the ternary system, and the mechanism for the penetration of the phase Nd₂Zr₂O₇ into the ternary system has been established.     

Phase equilibria in Cu-As(Sb,Bi)-O systems under conditions of the existence of a copper-based alloy

Solubility surfaces of components in metal melts for the Cu-As-O, Cu-Sb-O, and Cu-Bi-O systems in the range t = 1100–1300°C and high-temperature fragments of phase diagrams of oxide systems Cu₂O-R₂O₃ (R is As, Sb, Bi) are constructed based on thermodynamic calculations. Phase equilibria in the Cu-Sb-O and Cu-Bi-O systems are investigated experimentally. The results can be used to analyze the production processes of copper and copper-based alloys.