Present conditions of the industry and the facing problems

At present,most of the domestically pro-duced nonferrous metals are in the stateof over supply including copper,alumini-um,lead,zinc,nickel,tin,antimony andmagnesium.Among them,the productionof lead,nickel,tin and magnesium all ex-ceed demand by one or more times.Stricken by the world economic situation,particularly the economic crisis in theSoutheast Asian countries,all major metal     

The effect of conditions of preparation on the strength of WC — Co hard alloys and the relationship between the strength of these alloys and their structure and composition

Conclusions This paper presents a review of investigations which elucidated the effect of the technological conditions of obtaining the initial tungsten powder and the grinding and sintering conditions on the strength of a hard alloy during bending. An analysis of the results of these investigations shows that the differences in the strength of alloys differing in carbide grain size is primarily due to various manufacturing conditions and not to differences in grain size.On applying various methods of regulating the size of the carbide grain, sharply different changes in alloy strength are observed. The influence of the size of the grain was not noted, since it was suppressed by the greater effect of the technological factors.On excluding the effect of changing the sintering temperature (and other variable technological factors) the dependence of the alloy strength on the cobalt content changes its form: the maximum strength between 15 and 25% cobalt, noted in many researches, is not observed in this case. The strength increases continually up to 50% cobalt.The dependence on grain size with various methods of regulating carbide dispersity, and the dependence of the strength on the cobalt content on excluding the effect of the technological factors differ substantially from the regularities described by Gurland [1].The theoretical theses of Gurland are ungrounded, inasmuch as the strength relations are at variance with them, when the effect of the technological factors is excluded.The relations actually existing may be explained on the basis of the skeleton structure of the carbide and cobalt phases.     

Development of nanometer scale structures in composites of NbTi and their effect on the superconducting critical current density

A detailed investigation has been made of an optimized, high critical current density composite of Nb-46.5 wt% Ti. Details of the fabrication of the composite are given and an extensive metallurigical characterization of the microstructure at many stages in the fabrication and optimization process is presented. It is shown that up to 20% of α-Ti is produced by the heat treatment process. The mechanism by which the precipitate distribution is refined with increasing number of heat treatment and initially equaixed precipitates turned into very thin, high aspect ratio ribbons by large drawing strains is quantitatively described. Critical current density measurements show that the optimum pinning forces are obtained for precipitates of ~1 nm in thickness, spaced ~4 nm apart. These dimensions are considerably smaller than those previously reported. There appears to be little or no proximity effect suppression of the pinning force even though the precipitate thickness is of order 0.2 coherence length. The specific pinning force of the precipitates ranges from 170 to 260 N/m², a value similar to that measured earlier for grain boundary film precipitation in this alloy.     

Misoriented dislocation substructures and the fracture of polycrystalline Cu–Al alloys

The evolution of the dislocation substructure in polycrystalline Cu–Al alloys with various grain sizes is studied during deformation to failure. A relation between the fracture of the alloys and the forming misorientation dislocation substructures is revealed. Microcracks in the alloy are found to form along grain boundaries and the boundaries of misoriented dislocation cells and microtwins.     

Dislocation transformations and the anomalies of deformation characteristics in TiAl—I. Models of dislocation blocking

An analysis is given of the models proposed to explain the temperature peak of yield point in TiAl. Results are provided of a theoretical investigation into the glissile dislocations of different types and of transmission electron microscopy (TEM) observations of nodes formed by these dislocations. Consideration is given to mechanisms of superdislocation blocking due to their resplitting into noncoplanar configurations such as “roof”-type barriers, barriers of the two-layer twin type, barriers similar to Kear-Wilsdorf locks and Lomer-Cottrell-Hirth barriers. A new blocking mechanism related to trapping of single dislocations in deep Peierls valleys is proposed.     

Influence of crystallization conditions on the structure and modifying ability of Al–Sc alloys

The influence of the modes of thermal-and-temporal treatment and cooling rate of metallic alloys on crystallization regularities of Al–Sc alloys and their structure, properties, and modifying ability are established. Castings of Al–Sc alloy, which were prepared by the electrolysis of salt melts KF–NaF–AlF₃–Sc₂O₃ at 820–850°C, are used as the initial charge for casting. It is established that, by varying the magnitude of melt overheating and casting temperature, it is possible to vary the crystal shape, amount, and size in wide limits. The modifying action of cast and rapidly quenched master alloys, as well as the master alloy produced by electrolysis, is tested for Al–4.5% Cu alloy. The largest effect of milling the structure of the Al–4.5% Cu–0.4% Sc alloy is attained when using the rapidly quenched master alloy.     

Self-diffusion in α-iron: The influence of dislocations and the effect of the magnetic phase transition

Self-diffusion in dislocated α-iron single crystals has been studied with the radioactive tracer ⁵⁹Fe in the temperature range 754–1163 K. Serial sectioning was performed either by microtome cutting or by sputtering. Based on systematic studies of diffusion along dislocations in the same material by the present authors [in DIMETA 88—Diffusion in Metals and Alloys (edited by F. J. Kedves and D. L. Beke). Defect and Diffusion Forum 66–69, 591 (1989)] lattice diffusion coefficients have been selected by considering the influence of dislocations on the apparent diffusivities measured in dislocated crystals. The temperature dependence of the lattice self-diffusion coefficient shows a deviation from the Arrhenius behaviour due to the magnetic order-disorder transition. The general relations and several semi-empirical models which describe this magnetic diffusion anomaly are discussed. From fits of the respective models to a set of lattice diffusion coefficients activation parameters for self-diffusion in the ferromagnetic state (D_f⁰ and Q_f) and in the completely disordered paramagnetic state (D_p⁰ and Q_p) are obtained: D_f⁰ = 6.8–27.7 · 10⁻⁴ m² s⁻¹, Q_f = 2.95–3.10 eV, D_p⁰ = 6.8–12.3 · 10⁻⁴ m² s⁻¹, and Q_p = 2.57–2.68 eV. Independent of the details of these models the parameters fall within fairly narrow limits.     

Recycling of aluminum – effect of fluoride additions on the salt viscosity and on the alumina dissolution

The objectives of this work are to study the influence of fluoride additions to molten salt flux used in aluminum recycling on the viscosity and on the dissolution of alumina. These parameters were studied to clarify the phenomena that occur inside the rotary furnace, because there is still very little fundamental research about this process. First, an apparatus was set to measure the viscosity of molten salt fluxes. Second, equimolar mixtures of NaCl and KCl with NaF, KF and CaF₂ additions up to 5 wt% were prepared and melted in a laboratory furnace. Alumina rods were immersed in the molten flux, and the measurements of the reduction of the external diameter were taken at periodic times. The additions of fluorides diminish the viscosity of the equimolar mixture of NaCl and KCl, and fluoride additions also improve the dissolution velocity and corrosive attack on alumina.     

Dislocation transformations and the anomalies of deformation characteristics in TiAl—II. The structure of dislocation ensemble: Experiment and theory

Results of an electron microscope investigation of dislocations in TiAl are presented. An analysis made of typical dislocation configurations such as blocked single dislocations and blocked superdislocations-traps for single dislocations. Theoretical models are assigned to the configurations observed. Fundamentals of a phenomenological approach to describe plastic deformation are outlined. This approach enables allowance for dislocation transformations of several types. An analysis of the dislocation transformations is made, with a view to reveal those which may be responsible for the temperature peak of the yield stress. The concepts of the possible structure of the dislocation ensemble in TiAl are formulated.     

Effect of the solidification and aging conditions on the mechanical properties of Pb–Ca–Sn battery alloys

The influence of the mold temperature on the mechanical properties and the structure of Pb–Ca–Sn battery alloys during their solidification and subsequent aging is studied.     

The effect of lamotrigine and carbamazepine on the development of the audiogenic seizure reaction in rats of the Krushinski?-Molodkina strain

The effect of Lamotrigine and carbamazepine on the development and character of the epileptiform seizures after strong sonic stimulation were studied on Krushinski?-Molodkina line of rats. Both drugs manifested a dose-dependent increase in the latency of motor reaction Lamotrigine administration in the dose range of 5-40 mg/kg, i.p., resulted in a moderate decrease in the seizure intensity preventing predominantly the tonic component of the seizure and failed to modify the character of convulsive reaction. Carbamazepine administered in doses of 7.5-30 mg/kg effectively prevented the epileptiform seizures. The "two-wave" motor reaction was observed in 15% of carbamazepine-treated rats.     

TEM-in situ deformation of beryllium single crystals—a new explanation for the anomalous temperature dependence of the critical resolved shear stress for prismatic slip

The critical resolved shear stress for prismatic slip within beryllium single crystals passes through a maximum in the temperature range of 170–450 K. A valid explanation has not been found till now. In the present paper the experimental results of TEM-in situ deformation of single crystal beryllium are presented. Although the samples were oriented to promote prismatic slip, combined slip mechanisms on prismatic and basal planes were observed at room temperature. However, at 170 K plastic deformation only occurred by prismatic slip. A new model explaining the anomaly of the critical resolved shear stress is proposed which is based on elementary dislocation processes, i.e. formation and motion of salient points on dislocation lines. The same mechanisms might also result for other hexagoanl metals in a comparable anomaly of the plastic behavior.     

Effect of quenching conditions on the structure and properties of a “thick” microwire fabricated by the Ulitovskii-Taylor method

The effect of quenching conditions on the mechanical and magnetic properties of a meltquenched wire with a core diameter of 50 μm, which is made of a model soft magnetic Co₆₉Fe₄Cr₄Si₁₂B₁₁ alloy and is fabricated by the Ulitovskii-Taylor method, is studied. The highest set of mechanical and soft magnetic properties of a wire is achieved when it is quenched from the upper position of a quenching stream. The lowering of the position of the quenching stream degrades the mechanical and magnetic properties of the wire at a retained amorphous structure in it.     

And now what, after such tribulations? Memory and dislocation in the era of uprooting.

This article explores some of the often overlooked, traumatic psychological consequences that follow from major social and political disruption and upheaval. Specifically, it examines the importance of maintaining memory and legacy in the face of widespread uprootedness and dislocation of the sort that can undermine and even obliterate personal, social, and collective identities. The role that authentic social frameworks for memory play in preserving psychological rootedness and that accurate historical narratives play in resistance and regrouping is explored. Finally, the importance of creating a new psychology that is fully grounded in history and culture is emphasized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)