Observation of cold-rolling texture and partially recrystallized texture in polycrystalline 3 pct Si-Fe by high-resolution electron backscattered diffraction

Cold-rolling texture and partially recrystallized texture of polycrystalline 3 pct Si-Fe were investigated using high-resolution electron backscattered diffraction (EBSD) method. From the measurement on a deformed grain with {211}〈011〉∼{111}〈011〉 orientations, deformation bands with {12 4 1}〈014〉 orientation were found. It turned out that the orientation rotation relationship between deformation bands and surrounding deformed grain can be explained by the activation of the slip system, which has a common slip plane with an adjacent grain. Oriented nucleation of recrystallized grains with {12 4 1}〈014〉 orientation was observed in a deformed grain with {211}〈011〉∼{111}〈011〉 orientation. Exactly the same orientation relationship that was observed between deformed grain and the deformation bands was also observed between the deformed grain and the recrystallized grain. A hypothesis that recrystallization nuclei are generated directly from the deformation bands formed by an activation of the slip system that has a common slip plane of neighboring deformed grains was proposed from the present experimental results.     

Thermodynamic calculations for Nb-containing high-speed steels and white-cast-iron alloys

Thermodynamical equilibria have been calculated for a wide variety of high-speed steel compositions belonging to the multicomponent system Fe-C-W-Mo-V-Cr-Nb as well as for two series of white-cast-iron alloys containing niobium. Some temperature-concentration diagrams for both classes of alloys are presented and calculated quantities (melting and transformation temperatures, amounts and compositions of phases) are compared with experimental data. Good agreement between calculated and experimental information has been obtained, with the exception of the MC phase compositions and transformation temperatures for white-cast-iron alloys with high carbon and chromium contents. These differences can, however, be satisfactorily explained by plausible kinetic effects.     

Thin-film nickel coatings on fiber materials

Vacuum deposition of thin films onto fiber materials is a promising method of obtaining electromagnetic screens. We have studied the structure and the electromagnetic properties of machine-knitted fabric coated with nickel by means of magnetron sputtering. When the fabric is irradiated from the metal-coated side, the reflection coefficient is higher by a factor of 1.4 as compared to the case when the same source of electromagnetic radiation is situated on the opposite side (facing the uncoated surface), while the absorption coefficient in both cases is the same.     

Calciothermic reduction of titanium oxide in molten CaCl<Subscript>2</Subscript>

Titanium oxides were reduced to metallic titanium using the liquid calcium floating on the molten CaCl₂. A part of Ca dissolved into CaCl₂ and reacted with TiO₂ settled below CaCl₂. The by-product CaO also dissolved by about 20 mol pct into CaCl₂, which was effective in reducing the oxygen concentration in the obtained Ti particles. The compositional region in the Ca-CaCl₂-CaO system was examined for the less oxygen contamination in Ti and the better handling in leaching. A large amount of the residual calcium oxidized the titanium powder in leaching. The metallic Ti powder less than 1000 mass ppm oxygen could be obtained only for 3.6 ks using 5 to 7 mol pct Ca-CaCl₂ at 1173 K. The powder was slightly sintered like sponge, and contained approximately 1500 ppm Ca. The anatase phae, the intermediate product in the refining process of TiO₂, could be also supplied as raw material as well as rutile.     

The electrochemical behaviour of nitrogen-containing austenitic stainless steel in methanolic solution

The corrosion behaviour of nitrogen-containing austenitic stainless steel in methanol containing different concentrations of H₂SO₄, HCl, LiCl and H₂SO₄ + HCl has been investigated using a potentiostatic polarization method. The cathodic reaction in the H₂SO₄, HCl and H₂SO₄ + HCl solutions was proton reduction whereas in the neutral LiCl solution, oxygen reduction was the predominant cathodic reaction. Active, passive and transpassive behaviours were observed only for higher concentrations of H₂SO₄ (0.01–2.0 M) due to the inherent water content. A cathodic loop, characterized by measured negative current in the anodic region, was also observed in solutions, in which the concentration of H₂SO₄ was 1.0 M or higher. The relative stability of the passive films decreased as the H₂SO₄ concentration increased, and thus the steel suffered from mild pitting corrosion. In the chloride environment, the rate of corrosion increased as the Cl⁻ ion concentration increased. The presence of acid along with Cl⁻ ions enhanced corrosion, and the corrosion rate increased significantly. The steel suffered from mild intergranular corrosion in acidic chloride solutions of methanol. In the H₂SO₄ + HCl solutions, passive films were only formed when the H₂SO₄ to HCl concentration ratio was greater than ∼10:1.     

Application of holographic interferometry for determining the solubility of gases in liquids

The effect of a gas dissolved in a liquid on the variation of the refractive index of the compressed mixture was studied. The compression process was monitored with the aid of a holographic interferometer. The sensitivity of this method allows the compressibility of water and the solubility of helium and nitrogen to be studied at pressures below 4 atm. A procedure for obtaining qualitative and quantitative data on the solubility of gases in liquids is proposed.     

Atomic hydrogen flux density measured using thin metal films

Using one-or two-layer films of transition metals, it is possible to determine the atomic hydrogen flux density under reduced gas pressure conditions (10⁻¹–10⁻³ Pa). The method consists in monitoring a change in the film resistance caused by selective dissolution of atomic hydrogen in the metal during exposure of the film in a mixed atomic-molecular flow, followed by determining a characteristic time τ required for the hydrogen concentration in the film to reach 63% of the maximum possible level. The hydrogen flux density is then calculated within the framework of a simple mathematical model of the film saturation with hydrogen described by a relaxation law. The proposed method is characterized by a high selective sensitivity to atomic hydrogen. The atomic hydrogen flux density in a mixed atomic-molecular flow can be determined in a range from 5×10¹³ to 10¹⁶ cm⁻² s⁻¹.     

On the prospects of developing high-efficiency piezocomposites based on crystals of solid solutions of ferroelectric relaxors

Electromechanical properties of the 0-0-2-2 type composite based on platelike crystals of solid solutions of ferroelectric relaxors of the Pb(A_1/3Nb_2/3)O₃-PbTiO₃ system (A = Zn, Mg) have been studied for the first time. Factors accounting for the record values of some effective parameters of this composite are considered. The relationship between the components of the elastic compliance tensor of the layered structures forming the composite and the positions of maxima of the effective hydrostatic parameters is established.     

A bidirectional ring fiber laser with a 90° Faraday rotator as the nonreciprocal phase element. II. Experiment

The results of experimental investigation of an Er-doped fiber bidirectional ring laser with a 90° Faraday rotator in the cavity are presented. Two theoretically predicted regimes of the bidirectional generation of modes propagating in opposite directions with either complex-conjugate or orthoconjugate polarization states have been realized in practice. In each of these regimes, stable bidirectional generation of only one longitudinal mode propagating in each direction is possible. The former regime ensures significant stabilization of a nonreciprocal frequency shift between the modes propagating in opposite directions, this shift being determined by the Faraday phase rotator.