Applied Mechanics and Materials Vol. 682

Abstract: Using atomic force, optical and electron microscopy methods, the changes in the microstructure and phase composition were investigated for the alloy Nb47%Ti used for the manufacture of superconducting cable employed as current-carrying elements in the ITER magnetic system (abbr. for International Thermonuclear Experimental Reactor). The test samples were prepared from the superconducting wire at an intermediate step of the drawing process for the area reduction Ø1.3→Ø1.2 mm. The effect of cold drawing and intermediate annealing on the properties of as-worked Nb-Ti alloy was assessed. Local strain zones were found to occur in the rupture area. The shape and chemical composition of Nb-Ti wire was examined for both a defect-free area and the rupture area. A Nb diffusion barrier was found to occur in the copper matrix of Nb-Ti wire.

Abstract: The frictional behavior of sintered composite materials based on aluminum with high content of solid intermetallics and soft tin was investigated. It was found that at the moderate pressures and in absence of a liquid lubricant, both types of composites exhibit a low friction coefficient and good wear resistance.

Abstract: In this study the structure and properties of surface layers obtained on cp-titanium workpieces by non-vacuum electron beam cladding of titanium carbide powder were investigated. The structure of modified materials was examined by optical microscopy and scanning electron microscopy. It was shown that the cladded layer had a high quality and thickness of about 2.3 mm. The cladded layer microstructure consisted of high-strength titanium carbide crystals distributed in titanium matrix. Morphology of titanium carbide particles and their volume fraction changed in the direction from the surface layer to the heat affected zone. The average microhardness value of the cladded layer was ~500 HV. Surface alloyed layers were of higher wear resistance compared to cp-titanium.

Abstract: In current research composite copper/tantalum were used as interlayer for explosive welding of titanium and Ni-based alloy sheets. Defects such as cracks coupled with brittle intermetallics compounds were not detected at the interface of dissimilar materials by metallographic analysis. Strength test of obtained composite material reveals growth of yield strength in 2 times in comparison with Ni-based alloy.

Abstract: Restructuring process of vacancy voids under the influence of post-cascade shock waves is studied by molecular dynamics method. It is shown that depending on the time gaps, which generate waves, voids can either be combined into a single complex, or break up into separate parts.

Abstract: In this paper the results of alumina aqueous suspension disaggregation with the help of bead and ball mills are shown. The changing of maximum particle size for50 wt. % and 90 wt. % of powder (from lowest to highest size) in suspension dispersed by a bead mill for one hour and ball mill for 48 hours was fixed. In order to achieve powder parameters given by the manufacturer disaggregating process sets was defined.

Abstract: Influence of welding position and gap between samples on efficiency of hybrid laser-arc welding (HLAW), geometry of melting zone and alloys of filler material depth penetration are presented in the publication. Studies were indicated that maximal efficiency (thermodynamic efficiency about 43%) was achieved at hybrid laser-arc welding in PG welding position. Efficiency at PA and PC welding positions were 31.8% and 33.8% accordingly. Researches were indicated that melting zone, depth penetration alloys of filler materials and efficiency of HLAW increase with increasing gap. Experiments were indicated, that depth penetrate of filler material alloys is 20 mm (gap 1 mm). Proportion of filler material in a top part of metal seam is 50%, in bottom part of metal seam is about 5%.

Abstract: Differential hardening of rails by compressed air at different regimes is accompanied by formation of morphologically different structure, being formed according to the diffusion mechanism of γ ↔ α transformation and consisting of grains of lamellar pearlite, free ferrite and grains of ferrite-carbide mixture.By methods of transmission electron microscopy the layer by layer analysis of differentially hardened rails has been carried out, the quantitative parameters of the structure, phase composition and dislocation substructure have been established and their comparison has been made for different regimes of hardening. It has been found that the structure-phase states being formed have gradient character, defined by the hardening regime, direction of study from the tread contact surface and by depth of location of layer under study.

Abstract: Efficiency of the dedusting of flue gases of the technological processes is reached at the expense of the new constructive solution of the cyclonic device in which possibility of the regulation of its geometrical parameters depending on properties and characteristics of the air-and-coal environment is provided. Results of pilot studies are presented, the engineering calculation procedure and a choice of the sizes of such devices is developed