Increase in the density of β-FeSi2 nanoclusters on a Si(111) surface by means of Si(111) √3 × √3R30°-B reconstruction

The formation of iron disilicide (β-FeSi₂) nanoclusters as a result of solid-state epitaxy at T = 500–700°C and an iron coverage of 0.05–0.5 monolayer on a boron-modified Si(111)√3 × √3 R30° surface has been studied by scanning tunneling microscopy. It is established that the number density of β-FeSi₂ nanoclusters on the Si(111) √3 × √3 R30°-B surface significantly exceeds the density of silicide clusters formed on the atomically clean Si(111) surface with a 7 × 7 reconstruction for the analogous iron coverages and annealing temperatures. At the same time, the density of point defects and clusters possessing metallic conductivity on the Si(111) √3 × √3 R30°-B surface is several orders of magnitude lower than on the Si(111)7 × 7 surface treated under identical conditions.     

Metal oxide bicrystal Josephson junctions of a new type with high critical parameters

Film bicrystal Josephson junctions of a new type based on a metal oxide high-T _c superconductor of the YBa₂Cu₃O_7−x (YBCO) system are suggested and studied. In junctions of the new type, in contrast to the known ones, the working surfaces situated on the opposite sides of the bicrystal interface have different crystal orientations: one is (001)YBCO, and the other is rotated (misoriented) relative to it by an asymmetric bicrystal angle around a certain axis lying in the substrate plane. The main electrical and dynamic (microwave) characteristics have been determined for junctions of the new type based on NdGaO₃ bicrystal substrates with the misorientation angle varying from 13° to 28°. These junctions exhibit high values of the critical parameters at T=77 K, including the critical current density I _C= (2–5)×10⁵ A/cm² and the characteristic voltage V _C=I _C R _N=0.6–0.9 mV. Advantages of the bicrystal Josephson junctions of the new type over the known junctions are considered.     

High-Temperature Strength of Niobium Alloy 5VMTs with a Silicide-Ceramic Coating. Part 1. Short-Term Strength Characteristics

Experimental data on the short-term strength and plasticity of niobium alloy 5VMTs of the system Nb–W–Mo–Zr in its initial state, after annealing, and with a silicide-ceramic protective coating obtained by testing in vacuum, an inert atmosphere, and in air in the temperature range from 290 to 2270 K are analyzed. The process of microcrack initiation and propagation in the protective coating and matrix is investigated in high-temperature static tension. The limiting plastic strain values have been established at which the composite retains its load-carrying capacity in high- temperature aggressive and oxidizing gas atmospheres.     

Measurement of the Total Range and Specific Energy Deposition of a Beam of Uranium Ions in Porous Carbon Targets

Experimental results on the total range and specific energy deposition of a beam of uranium ions in foam carbon targets with various densities are presented. The chaotic arrangement of graphite grains in a porous target is modeled theoretically and the influence of the porosity on ion stopping is investigated.     

Influence of dendritic crystallization on the structure and properties of continuous-cast pipe blanks

The influence of dendritic crystallization on the structure and properties of continuous-cast pipe blanks (diameter 150 mm) made from steel with 0.2% C is studied, in the cast and heat-treated states. Dendritic crystallization results in different chemical composition of the austenite and the boundary between the crystals, with different properties. That affects the structure of the steel. Besides the familiar factors, the improvement in the mechanical properties of cast subeutectoid steel after heat treatment is associated with the formation of impurity-rich ferrite in segregated sections of the dendritic structure.     

More efficient operation of the dust-free coke-discharge modules at OAO Zaporozhkoks coke batteries 5 and 6

Two types of dust-free coke-discharge modules are generally employed. The modules employed at OAO Zaporozhkoks are described and analyzed. Methods are proposed for determining their operational efficiency and testing their performance in plant conditions. Recommendations are made for improving the operational efficiency of dust-free coke-discharge modules mounted on door-opening machines.