Solid State Phenomena Vol. 303

Abstract: The processing conditions of the of electronic wastes are largely dependent on environmental standards and requirements. Modern technologies for processing electronic waste should meet the increased demand for metals as well as the requirements. Electronic wastes can be classified as hazardous materials, as household and industrial electrical devices, which contain components such as batteries, capacitors, cathode ray tubes, etc. Electronic waste can consist of a large number of components of various sizes, shapes and chemical composition. Some of them contain hazardous metals, including mercury, lead, cadmium. The presence of precious metals in electronic waste such as gold, silver, platinum, palladium, as well as non-ferrous metals (copper, nickel, zinc, tin, etc.) make it attractive for processing. In industry, both hydrometallurgical and pyrometallurgical methods are used to extract valuable metals from electronic waste. Applied technologies may have both advantages and disadvantages.

Abstract: The results of experimental studies of the thin surface layer of samples made of steel 45 after treatment with surface plastic deformation (SPD) multiradius roller (MR-roller) are presented. On the basis of the apparatus of the mechanics of technological inheritance, taking into account the effect of the solidified body, a model of the process according to the scheme of multiple loading-unloading of metal, taking into account the phenomenology of the SPD process and the properties of the material, is created. Distributions of parameters of the stress-strain state in the deformation centre are obtained, the parameters of roughness and microhardness of the surface layer are investigated.

Abstract: The paper presents the results of the analysis of the state diagram of compounds in the system А1₂O₃-SiO₂. It has been found that the presence and the concentration of oxygen have a very important effect on formation of compounds with a crystalline structure in different syngony based on SIALON. Oxygen contributes to transition of the metastable Al_XSi_3-XN₄compound into stable one. The parameter of structural “friability” of compounds has been used in the analysis of thethermodynamic stability of compounds in the Al-Si-N-O system. It has been foundthat the SiAl₄O₂N₄ compound with the 12H-SIALON structure (Pearson symbol hP32) has the greatest thermodynamic stability among the compounds under study in this system.

Abstract: Designed experimental setup, and a prototype of the original devices for athermic relaxation of thermal residual stresses in openwork welded constructions of large dimensions for the rational use of energy high-frequency acoustic (ultrasonic) fields, conducted laboratory studies and pilot tests in real conditions of production. Ultrasonic relaxation when welding thin-walled constructions standard openwork rolled steel profiles 10 large dimensions (up to 3 x 10 m). It has been established that with a decrease in the time of ultrasonic relaxation, the efficiency of its use decreases somewhat. Therefore, in an industrial environment, it is advisable to use the duration of ultrasonic treatment in the range of 0.02-0.04 min per mm of weld length.

Abstract: The present study was conducted by transmission electron microscopy (TEM) in order to investigate the structure of multicomponent nickel-based alloy obtained by directional solidification and change in its phase composition at high-temperature annealing. All states of the alloy possessed monocrystalline structure with [001] orientation. The alloy under study contained other elements apart from Ni, such as: Al, Co, and also Mo, Cr, W, Ta, Re, and Ru. The alloy was investigated in three states after annealing for: 1) 118 h; 2) 372 h; 3) 1274 h at 1000°С. The basic phases that form the alloy were γ and γ′. In the state after annealing for 118 h Al₆(Re,Ru) phase was observed in an insignificant amount. After longer high temperature annealing new phases occurred, such as σ-phase and δ-phase, Laves phase. The structures occurring during annealing can be classified into four types: 1) quasi-cuboids, 2) anisotropic stripe structures, 3) anisotropic structures of striped type with σ-phase separation, 4) structureless zones with large two-phase areas.

Abstract: Investigations conducted by transmission electron microscopy on thin foils were aimed at studying the structural-phase state of heat-affected zone of the welding joint performed by modulated current at two welding modes: coarse-droplet and fine-droplet transfer. Welding was conducted on the austenitic steel 0.12С-18Cr-10Ni-1Ti-Fe using the facility UDI-203. Welding modes were: I_i = 175 А (coarse-droplet transfer) and 140 А (fine-droplet transfer). Welding was performed on thin foils sized 200 × 15 × 4 mm³. Investigations were focused on heat-affected zone at the distance of 1 mm from the weld line towards the base metal – the base metal zone and at the distance of 0.5 mm towards the welded metal – the welded metal zone. The studies showed that in the state before welding the steel matrix presents γ-phase (austenite), which has face-centered cubic (fcc) crystal lattice. Morphologically the steel structure is given as grains where defect structure is presented by only network dislocation substructure, and grains where along with the dislocation substructure there are mechanical (or deformation) microtwins in the form of packages of one, two and three systems. It was established that welding of steel 0.12С-18Cr-10Ni-1Ti-Fe by modulated current with coarse-droplet transfer leads to martensitic transformation γ → ε only in the welded metal zone. At fine-droplet transfer welding leads to martensitic transformation γ → ε both in the base metal zone and in the welded metal zone. In the welded metal zone phase transformation γ → ε occurs more intensively. It was revealed that crystal lattice distortion in the whole heat-affected zone at welding by modulated current has only plastic nature, irrespective of the welding mode. Welding by modulated current with fine-droplet transfer leads to lower internal stresses in the whole heat-affected zone.

Abstract: The present work summarizes and presents separate results obtained by the authors when investigating mesoscopic and microscopic internal stresses formed under the conditions of thermal and mechanical treatment of martensitic, pearlitic and austenitic steels. Internal stresses were investigated using the method based on the analysis of bend extinction contours. The results obtained on industrial steels were presented. The sources were described and examples of internal stresses induced by these sources were given. The nature of bending-torsion of the crystal lattice depending on the averaging volume was determined. It has been shown that in martensitic steels along with the increase in the averaging volume (carbide particle → separate martensitic lath → martensite packet→ martensitic plate → grain) the amplitude of bending-torsion of the crystal lattice decreases. The nature of distortions also changes. At large amplitudes and low volumes of averaging they are completely or partly elastic, at large volumes of averaging they are completely plastic. Thereby, distortions are fully driven by the excess dislocation density.

Abstract: The study of the steel/steel adhesive joint using digital image correlation method has been carried out. A correlation between the evolution of distributions of deformation regions on the surface of the adhesive joint and the stages on the deformation curve is revealed. It has been found that a destruction along the adhesive seam begins when the adhesive joint reaches total deformations of about 0.5%. The analysis of deformation fields on the steel surface have allowed revealing the formation of extensive tension regions with greatest deformations at the interface of loaded plates. An increase in the values of compression deformations at the ends of the patch and a significant increase in the areas of these regions have been revealed.

Abstract: Transmission electron microscopy investigations were carried out to study the structural-phase state of ultra-fine grain (UFG) titanium with the average grain size of ~0.2 μm, implanted with aluminum ions. Implantation was carried out on MEVVA-V.RU ion source at room temperature, exposure time of 5.25 h and ion implantation dosage of 1⋅10¹⁸ ion/cm². UFG-titanium was obtained by a combined multiple uniaxial compaction with rolling in grooved rolls and further annealing at 573 К for 1h. The specimens were investigated before and after implantation at a distance of 70-100 nm from the specimen surface. Concentration profile of aluminum implanted with α-Ti was obtained. It was revealed that the thickness of implanted layer was 200 nm, while maximum aluminum concentration was 70 at.%. Implantation of aluminum into titanium has resulted in formation of the whole number of phases having various crystal lattices, like β-Ti, TiAl₃, Ti₃Al, TiC and TiO₂. The areas of their localization, the sizes, distribution density and volume fractions were determined. Grain distribution functions by their sizes were built, and the average grain size was defined. The paper investigates the influence of implantation on the grain anisotropy factor. It was revealed that implantation leads to the decrease in the average transverse and longitudinal grain size of α-Ti and decrease in the anisotropy factor by three times. The yield stress and contributions of separate strengthening mechanisms before and after implantation were calculated. The implantation has resulted in increase in the yield stress by two times.

Abstract: The article is devoted to the modeling of structural-phase transformations during automatic MIG welding of high-strength steel X80 in a welded seam and the heat affected zone in the ANSYS / Mechanical package. Based on the results of numerical modeling the relationship between the initial morphology of the steel microstructure and the parameters of the weld seam geometry was revealed.