Effect of the kinematics of rotary rolling on the fineness of the structure of hypereutectoid silumins

It has been established experimentally that the internal layers of cylindrical semifinished products that are made of hypereutectoid silumins and contain embedded lengthwise pins do not intermix during rotary rolling. The experiment also determined that the angles through which different concentric internal layers of the semifinished product (ω₁ > ω₂ > ω₃) are twisted are different and depend on the radii of those layers (R′₁ > R′₂ > R′₃). This finding contradicts the hypothesis of rigid sections in the classical theory of the strength of materials. An analytic relation (empirical formula) is found to describe the pitch of the internal layers of metal flow in relation to the main parameters of the rotary-rolling operation (the feed angle α and deformation ε) and the radius of the given internal layer (R′_x). Another empirical formula is proposed to determine the angle of inclination of the helical lines along which the metal inside the rolled specimen is displaced. A mathematical model is constructed to describe the dependence of the ductility properties of hypereutectoid silumin alloys on changes in the dimensions of the silicon crystals in the alloys when semifinished products made of these alloys are deformed by rotary rolling. __________ Translated from Metallurg, No. 8, pp. 68–72, August, 2006.     

Influence of the nonequilibrium crystallization on the phase composition of the Al-Mo-Ti alloy

The phase composition, microstructure, and crystal structure of the AMT TU-48-4-366 (Technical Specifications) foundry alloy (which is used as the alloying material when smelting titanium alloys) are investigated by X-ray phase analysis, electron probe microanalysis, and microscopy. Lattice parameters of ?, p, and δ phases are calculated and their elemental composition is revealed. No formation of the Mo₃Al refractory phase (t _m = 2150°C) is observed during the primary crystallization of the Al-Mo-Ti foundry alloy in nonequilibrium conditions. Its presence in the refractory phase in the foundry alloy is caused by secondary crystallization processes, during which an ultradispersed mixture of Mo₃Al + Mo₃Al₈ + TiMoAl₆ phases is formed at temperatures 1311 and 1314°C. The ultradispersed silicon-containing σ phase with the Mo_2.4Ti_2.1Si_0.8Al_4.7 average composition, which was formed in nonequilibrium crystallization conditions, is revealed. Parameters and interplanar distances of its lattice are determined. It is established that the largest nonuniformity by molybdenum in peritectics of primary crystals occurs at a high crystallization rate, i.e., in the lower part of the Al-Mo-Ti ingot.     

Proceedings of the American Psychological Association for the legislative year 2007: Minutes of the Annual Meeting of the Council of Representatives and minutes of the meetings of the Board of Directors.

Provides the minutes of the Annual Meeting of the Council of Representatives February 16-18, 2007, Washington, DC, and August 9 and 13, 2007, San Francisco, CA, and minutes of the February, June, August, and December 2007 meetings of the Board of Directors. These minutes are the official record of the actions of the American Psychological Association taken during the year by both the Board of Directors (the Board) and the Council of Representatives (Council). The main topical headings are I. Minutes of Meetings; II. Elections, Awards, Membership, and Human Resources; III. Ethics; IV. Board of Directors; V. Divisions and State, Provincial, and Territorial Psychological Associations; VI. Organization of the APA; VII. Publications and Communications; VIII. Convention Affairs; IX. Educational Affairs; X. Professional Affairs; XI. Scientific Affairs; XII. Public Interest; XIII. Ethnic Minority Affairs; XIV. International Affairs; XV. Central Office; and XVI. Financial Affairs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of the relation between the characteristics of the two-phase matrix structure for the random distribution of nonequiaxial inclusions in the body bulk

To describe the volume distribution of inclusions in the two-phase matrix structure, it is proposed to use a new characteristic of the magnitude of the projection (Π) of inclusions from the layer of a definite thickness on the mutually orthogonal planes, which depends on the mutual arrangement of inclusions and the projection plane under consideration for the concrete structure. The value of Π also depends on the thickness L of the analyzed layer of metal, which is described using two additional characteristics A and B. The relations between the conventional parameters of the matrix structure and new ones, namely, Π, A, and B, are analyzed.     

Evaluation of the accuracy of the three-dimensional size distribution estimated from the schwartz-saltykov method

The validity of estimation of the three-dimensional size distribution (3-DSD) using the Schwartz-Saltykov (SS) method has been evaluated by applying the discrete two-dimensional size-distribution (2-DSD) model. The coefficient for the SS method has been generalized, and the verification of this method has been studied by focusing on the measured number of sectioned particles on the cross section of the specimen, the step width of the histogram for the SS method, and the oversight of small sectioned particles. The total number of particles per unit volume (total N _V (T.N _V )) and the number of particles in each size class, estimated by the SS method, are found to be always underestimated compared with the true N _V value, without regard to the oversight of small sections. The T.N _V value can be reasonably estimated by an extrapolation method, in which the step width of the histogram approaches zero. The relative frequency in a distribution function is correctly determined independent of the step width when the oversight involves a sectioned particle size equal to or less than one-tenth of the true mean diameter of the particles. The quantitative 3-DSD can be obtained from the reasonably estimated value of T.N _V and the correctly determined relative frequency.     

Investigation of the surface of the liquidus of the Fe-Ni-S system at X s<0.51

Methods of thermal analysis, X-ray, optical, and electron microscopy were used to study the liquidus surface of the Fe-Ni-S system in the field of 35 to 51 at. pct sulfur. The FeS-NiS, FeS-Ni₃S₂, Fe_0.55S_0.45-Ni_0.55S_0.45, and Fe_0.61S_0.39-Ni_0.61S_0.39 sections and some additional samples were examined. A microscopic study of the samples slowly cooled and annealed enabled referring of all the samples to the fields of primary crystallization of the monosulfide solid solution (Fe _x Ni_1−x )S_1+y (MSS), the Fe-Ni solid solution with the γ-Fe structure (TN), and the (Fe _x Ni_1−x )_3±y S₂ heazlewoodite solid solution (HZSS). The data, obtained by a method of derivative thermal analysis, have been used to describe analytically the MSS and HZSS surface of primary crystallization. Previous results were used together with our own data to construct the TN surface of primary crystallization. These parts of the liquidus surface have been approximated by polynomial equations, the coefficients of which were determined by the least-squares method. As a result of the absence of experimental data in the δ-Fe-based solid-solution primary crystallization field, this liquidus part is approximated on the basis of the Fe-S and Ni-Fe phase diagram data. The equations are used to construct the boundaries between various areas of phase primary crystallization, to define the coordinates of a triple point, and to construct isotherms.     

Proceedings of the American Psychological Association, Incorporated, for the Legislative Year 2002: Minutes of the Annual Meeting of the Council of Representatives and Minutes of the Meetings of the Board of Directors.

Presents the Minutes of the Annual Meeting of the Council of Representatives, held February 15-17, 2002 in Washington, DC, and August 21 and 25, 2002 in Chicago, Illinois. Also included are the Minutes of the February, June, August, September, and December 2002 Meetings of the Board of Directors. These minutes are arranged in topical rather than chronological order, and subheadings are used when appropriate. The main topical headings are: I. Minutes of Meetings; II. Elections, Awards, Membership, and Human Resources; III. Ethics; IV. Board of Directors; V. Divisions and State and Provincial Psychological Associations; VI. Organization of the APA; VII. Publications and Communications; VIII. Convention Affairs; IX. Educational Affairs; X. Professional Affairs; XI. Scientific Affairs; XII. Public Interest; XIII. Ethnic Minority Affairs; XIV. International Affairs; XV. Central Office; XVI. Financial Affairs; and XVII. Communications Concerning Outside Organizations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigation of the effect of the cooling mode on the quality of alumina-containing cakes

It has been established under laboratory conditions that there is an increase in the β-C₂S content and a decrease in the α′-C₂S content when the nepheline cake is held for τ = 0–30 min in a temperature range of 630–680°C. Specifically, industrial tests on a fire grate cooler confirmed the effect that the duration of holding the cake at T = 630–680°C exerts on its quality; an increase in τ from 1.6 to 4.9 min led to an increase in the β-C₂S content by 3% and an increase in the α′-C₂S content by 4%.     

On the origin of the R orientation in the recrystallization textures of aluminum alloys

The crystallographic textures of most Al alloys, after rolling and recrystallization, are composed of two components, the cube orientation {001}〈100〉 and a component similar to the former rolling texture, the so-called R orientation {124}〈211〉. The R orientation can be retained from the rolling texture in cases where the stored dislocation energy is being reduced merely through extended recovery reactions, which is referred to as continuous recrystallization. In addition, R-oriented grains can form through genuine, discontinuous recrystallization by nucleation within S-oriented grains at the grain boundaries between the deformed bands and a subsequent growth selection as caused by orientation pinning. The strength of the R orientation in the recrystallization textures strongly depends on the pretreatment and processing parameters of the material and, in particular, on the alloy investigated. The present article gives a survey of the factors affecting the R orientation and reviews recent results on the formation mechanisms of this orientation, which have been obtained by local texture analysis. The results are discussed with regard to the competition of the R orientation with the cube orientation during the evolution of the recrystallization textures in Al alloys.     

Projection of the solidus surface of the Sc-Ti-Ni system in the region of TiNi-Ni-ScNi alloys

Metallographic, x-ray diffraction, electron probe, and differential thermal analyses are used to study, the interaction of components of TiNi-Ni-ScNi alloys in the Sc-Ti-Ni system at subsolidus temperatures. The vertical section between TiNi and ScNi is shown to be quasibinary. No ternary compounds are observed in the TiNi-Sc-ScNi system. Six single-phase, nine two-phase, and four three-phase fields are found on the solidus of the TiNi-Ni-ScNi system. A characteristic feature of the structure of alloys of the Sc-Ti-Ni system in the region TiNi-Ni-ScNi ε is that the E phase is in equilibrium with the phases based on TiNi(δ), Ni(γ), ScNi₂(λ₂), Sc₂Ni(v), SCNi₅(ξ), and ScNi(δ).     

Effect of the properties of the surface oxide layers on the oxidation of aluminum powders

Conclusions The oxidation of ASD-4 and AV-000 aluminum powders in the temperature range 293–1773°K has been studied by the thermogravimetry (under conditions of programmed heating), thermal argon desorption, and x-ray phase analysis methods. The stresses generated during heating in the outer oxide films on aluminum particles lead to the formation of cracks in the former, which promotes oxidation of the aluminum. Marked increases have been observed in the oxidation rate and specific surface of the ASD-4 powder at temperatures corresponding to the temperature range of the -Al₂O₃ transition. The finding appears to be linked with an increase in the intensity of crack formation during the polymorphic transformation and with enhanced diffusional mobility in the oxide layers.Translated from Poroshkovaya Metallurgiya, No. 2(302), pp. 1–5, February, 1988.     

Application of the invariant method for the determination of the thermodynamic properties of Zn-Ga liquid solutions

Abstract

On the basis of Krupkowski's formulae for the logarithm of the activity coefficient of components in binary solutions, a new method has been developed which results in the determina tion of the thermodynamic properties of solutions from eutectic-type phase diagrams. The method takes into account deviation from the regular solution model and can be used to predict the liquidus line. The. method is applied to the Zn-Ga system.

Résumé

On a mis au point une nouvelle méthode permettant le calcul des propriétés thermodynamiques de solutions à partir des diagrammes d' équilibre des phases pour les systémes eutectiques. La méthode est basée sur le formalisme de Krupkowski pour le logarithme des coefficients d'activité des composants d'une solution binaire. On tient compte des écarts au modéle des solutions régulières. La méthode, qui peut ëtre utilisée pour estimer les lignes liquidus, est appliquéeau système Zn-Ga.     

Determination of the phase boundaries of the wustite solid solution within the context of reduction tests

Oxygen reduction measurements performed isothermally on Fe₂O₃ with CO/CO₂ gas mixtures make it possible, in combination with a system of equations describing the homogeneous wustite phase FeO_n, to describe also the boundaries of this solid solution mathematically. Compared with corresponding data determined by Giddings and Gordon on the basis of a literature evaluation, the boundaries of the wustite field are found to shift to a much lower reduction potential. The developed system of equations makes it possible to plot the curves of the same oxygen concentration in the homogeneous wustite phase field of the Bauer-Glaessner diagram. When comparing the reduction equilibria of the left- and right-hand wustite solid solution boundary with the appropriate literature data there is a good agreement particularly with the measurements of Darken and Gurry. Significantly lower oxygen concentrations are found in the FeO phase diagram, however, especially at high temperatures. New concentration data derived from the systems of equations are also given for the melt equilibria of the wustite phase, which lead to the assertion that the liquidus curves of magnetite, wustite and iron are also shifted to a lower oxygen concentration. The decomposition point of the wustite is found at 570°C, 49.5 %, CO'₂ and 23.2 % oxygen.     

Application of the HeapSim model to the heap bioleaching of the Pueblo Viejo ore deposit

The HeapSim computer model can simulate column, crib, and heap leach processes for a variety of sulfide ores. In this work, the model was used to evaluate the feasibility of heap biooxidizing the high-grade pyrite ore from the Pueblo Viejo deposit in the Dominican Republic. Simulations have revealed few but critical conditions for the success of a full-scale heap.The heap should be inoculated with mesophiles and moderate thermophiles bacteria, as well as extreme thermophilic archaea at the start-up of the biooxidation pretreatment. These microorganisms were isolated from two slurry cultures collected at site and grown in the laboratory at different temperatures. All cell types may be indigenous to the site, but inoculation of the ore and leach solution with all cell types is necessary for the transition into different temperature regimes for best sulfide oxidation performance.To ensure that all parts of the heap achieve at least 65% sulfide oxidation in the planned 400 days of treatment, the heap height should be less than 8 m if aerated at 2 m³/m²/h and irrigated at 8 L/m²/h. These conditions would preclude the formation of “hot spots” that could inhibit even the extreme thermophiles. By increasing the aeration rate to 4 m³/m²/h and the irrigation rate to 11 L/m²/h, the heap could be stacked to 8 m. Large aeration and irrigation rates would lower the temperatures at the top and bottom of the heap. Under these conditions, all parts of the heap could be expected to achieve 65% sulfide oxidation in only 250 days, as indicated by the model.     

The Slenderness Ratio of the Filter Used in the Process of Liquid Steel Filtration as the Additional Parameter of the Filter Form

We propose in this publication the introduction of new, additional definition describing the multiple orifice ceramic filters used in research works on the liquid steel filtrations, calling this the filter slenderness ratio. In order to confirm the theoretical assumptions we have performed a series of the laboratory scale experiments (for the filter slenderness ratio S_F1 λ = 1.67 and S_F2 λ = 3.34). The influence of the filter slenderness on the filtration process efficiency has been determined through variations in quantities and surface shares of the non‐metallic inclusions in the filtrated steel in relation to the non‐filtered steel. We present also the results of researches on the separating surfaces between the liquid steel and the ceramic filter material, which in form of photos and scanning microscope microanalyses are put together in the publication.     

Deutonymphs of the genus Hirstionyssus of the fauna of the USSR (Acarina, Hirstionyssidae)

Described and figured are deutonymphs of 18 species of the genus Hirstionyssus Fonseca, 1948, parasites of small mammals (H. carnifex (L. C. Koch) Oudemans, 1913; H. blanchardi (Trouessart, 1904); H. ellobii Bregetova, 1956; H. myospalacis Zemskaja et Piontkovskaja, 1957; H. transiliensis Bregetova, 1956; H. georgicus Bregetova, 1956; H. sciurinus (Hirst, 1921); H. confucianus (Hirst, 1921); H. bregetovae Razumova, 1953; H. macedonicus (Hirst, 1921); H. pauli Willmann, 1952; H. criceti (Sulzer, 1774); H. latiscutatus (Meillon et Lavoipierre, 1944); H. apodemi Zuevsky, 1970; H. pavlovskii Zemskaja, 1959; H. soricis (Turk, 1945); H. meridianus Zemskaja, 1955; H. isabellinus Oudemans, 1913); Keys to deutonymphs of the genus Hirstionyssus are given for the first time.     

An investigation of the thermodynamics of solvent extraction of metals III. Prediction of the composition of the equilibrated organic phase

Based on the known composition of the aqueous phase, a thermodynamic extraction equilibrium model can be used to solve for the equilibrated organic component concentrations simultaneously. In this model, the non-ideality of both the organic and aqueous phase is considered. Several metal neutral solvent extraction systems, such as TBP—UO₂(NO₃)₂, (C₇H₁₅)₂SOUO₂(NO₃)₂ and TBP—UO₂Cl₂, have been used to verify the applicability of this model. The predicted compositions are in good agreement with the experimentally measured results.     

On the relation of the grüneisen parameter to the thermal stability of metals

The thermal stability of cubic metals in both solid and solid-liquid melt phases is discussed in terms of anharmonic effects such as due to Grüneisen parametery. A thermodynamic equation relating γ and a stability determinantD for solid metals is derived, followed by a presentation of the temperature dependence ofD. An analysis of the estimatedD values shows the stability determinant to be a direct function of temperature for the solid metals, but decreases on melting. The magnetic changei.e. second-order phase transformation of a solid metal is theoretically considered to be associated with a minimum of the Grüneisen parameter and a maximum in the intensity of energy fluctuation. Some thermodynamic equations involving γ and heat capacity are derived which relate the properties of a metal at the two-phase solid-liquid melt regime to its properties in the solid region. An analysis of the estimated data shows a very small increase in γ from the solid bulk to the melt phase. However, the heat capacity data which are expected to be fairly similar for all metals at fusion, are estimated to be different for metals in the melt regime and are higher compared to the corresponding values in the solid region.     

Thermodynamic Simulation of the Influence of the Temperature and the Basicity of a Boron-Containing Slag on Steel Desulfurization

The results of thermodynamic simulation of the desulfurization of a medium-carbon steel by slags of the CaO–SiO₂–MgO–Al₂O₃–B₂O₃ system are presented. The HSC Chemistry 6.12 software package is used for the simulation. The thermodynamic simulation is performed for 20 various chemical compositions of slags with various B₂O₃ contents (1–4%)¹ and basicities ((CaO)/(SiO₂) = 2–5). The computations are performed using the Equilibrium Compositions module in the temperature range from 1500 to 1700°C with an increment of 50°C at a gas phase pressure of 0.1 MPa. The main results of the calculations are presented as the dependences of the change in the sulfur content in steel [S] on the temperature, the content of B₂O₃, and the slag basicity. An increase in the temperature of metal desulfurization from 1500 to 1700°C exerts a favorable effect on the sulfur content for the studied range of slag basicities. In particular, the sulfur content in steel decreases from 0.012 to 0.009% when steel is processed with the slag having 3% B₂O₃ and a basicity (CaO)/(SiO₂) = 2. A positive effect of an increase in the slag basicity from 2 to 5 on metal desulfurization is observed: the degree of desulfurization increases from 61.1 to 97.2% at 1600°C and 3% B₂O₃ content in the slag. As the B₂O₃ content in a slag increases from 1 to 4%, its refining properties decrease significantly in the range of basicity not higher than 2. In the range of high slag basicities (3–4), the negative effect of acidic oxide B₂O₃ on the refining properties of the slag decreases, providing low sulfur contents (which do not exceed [S] = 0.003–0.004% at 4% B₂O₃). At a slag basicity of 5, the sulfur content in steel decreases to 0.001%, all other things being equal. The simulation results can be used for the calculation of steel desulfurization processed by slags containing B₂O₃.