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The works in the field of radiation materials science of target materials of neutron sources based on the subcritical assemblies controlled by linear accelerators of electrons or protons, so-called accelerator driven systems (ADS), are reviewed. Now, electronuclear ADS systems are the prototype of safe nuclear reactors of the 5th generation. In connection with the physical start-up of the neutron source facility of the National Scientific Centre ‘Kharkiv Institute of Physics and Technology’ of the N.A.S. of Ukraine (NSC ‘KhIPT’ NASU), the target of which is fabricated from powdered tungsten covered with tantalum, the issues of preparation technology, construction, and physical and mechanical properties of W–Ta materials of targets in non-irradiated and irradiated states are considered. The nuclear-physical processes of radiation damage to the target during co-irradiation of it with both neutrons of a subcritical assembly and high-energy e- and γ-beams are analyzed. The target resources of ADS systems are estimated. As noted, the difficulty of predicting the ‘survivability’ of the W–Ta target also relates to the fact that, except for the works carried out at the NSC ‘KhIPT’ NASU in 70–90th of the last century, there are no experimental works in the world on the radiation damage of reactor materials by high-energy electrons with an energy of 100 MeV and above.

Crystallographic-orientational and dimensional-morphological features of microstructure in welded joints of high-temperature nickel alloy single crystals are considered, depending on the initial crystallographic orientation and its change over the weld solidification macrofront. EBSD analysis and optical metallography methods were used to study the structural features of individual zones of welded joints of high-temperature nickel alloy single crystals. Their dependence on the initial crystallographic orientation of the welded joint and its change over the weld pool solidification macrofront is established. It is shown that alongside the predominant inheritance of base metal crystallographic orientation by the weld metal, formation of a grain structure of different crystallographic orientation, morphology, dimensions and nature, namely solidification and deformation-induced, can be in place. The mechanisms of formation of grains of the specified nature are considered. Boundaries of solidification type grains are the junction of dendrite blocks with different crystallographic orientation. Deformation type grains are the result of relaxation of microstresses at the stage of welded joint cooling, and they form in areas where the direction of acting stresses is the closest to the crystallographic orientation of easy slip. It was also found that deformation type grains can form both in the weld metal, and in the HAZ. At the same temperature conditions of making the welded joints, the quantitative and dimensional-orientational parameters of deformation structure of the HAZ metal correlate with similar parameters of weld structure elements. The possibility to produce welds without cracks with perfect single crystal structure is indicated. [ABSTRACT FROM AUTHOR]

According to the results of complex electrochemical, corrosion-mechanical and fractographic studies, the existence of three potential regions, in which the stress-corrosion cracking (SCC) of 17G1S (17G1S-U) steel in the NS4 model soil electrolyte occurs by different mechanisms was established and experimentally confirmed: at potentials positively than -0.8 V – by the mechanism of local anodic dissolution, at potentials region from -0.8 V to -0.98 V – by the mixed mechanism, at potentials less than -0.98 V by hydrogen breaking mechanism. The susceptibility to SCC of high-frequency weld joints, estimated by the coefficient of KS, in the potential range from the corrosion potential to -1.2 V increases (KS increases from 1.1 to 1.8), which is less intense than for steel 17G1S/17G1S-U (KS increases from 1.1 to 2.8), for arc weld joints – does not change much enough (KS increases from 1.1 to 1.3). The validity of KS coefficient introduced for the base metal for comparative assessment of the susceptibility to SCC of welded joints, is provided in case that there are no defects in the welds and SCC occurs on base metal.

A short historical review of stages of formation of the G. V. Kurdyumov Institute for Metal Physics (N.A.S. of Ukraine) in connection with its 75th anniversary is presented. (According to both the decree of the Council of Peoples Commissars of the Ukrainian S.S.R. of 15 November, 1945 and the decision of Presidium of the Academy of Sciences of the Ukrainian S.S.R. of 21 December, 1945, Laboratory of Metal Physics at the Academy of Sciences of the Ukrainian S.S.R. began to work since 1 January, 1946.) The basic achievements of metal physicists of the Institute along the past decades are briefly identified, and promising trends of metal physics research in Ukraine are outlined. [ABSTRACT FROM AUTHOR]

The article analyzes the methods of modernization of optical microscopes to obtain digital images and simplifies their subsequent analysis while conducting basic metallographic examinations of deposited metal specimens. Two main methods of modernization were considered: with the help of a camera, equipped with special adapters, which is attached to the tube of the microscope eye-piece and with the help of a video eyepiece, which is installed instead of a standard microscope eyepiece. The main advantages and disadvantages of each method were noted. Using MIM-7 metallographic microscope, Canon 650D camera, SIGETA MCMOS 3100 video eyepiece, as well as specimens of microsections with a deposited layer of semi-heat-resistant steel of C – Cr – Mo – W – V alloying system, comparative metallographic examinations were performed. It is shown that the use of a special video eyepiece SIGETA MCMOS 3100 allows obtaining better digital images of metal microstructures. As an illustration of the main advantages of the work, provided by the use of the equipment modernized in this way, the results of metallographic examination of metal, deposited by electric arc method using flux-cored wire PP-NP-120V3KhMF, were provided. It was experimentally established that the Toupview software, supplied with the eyepiece SIGETA MCMOS 3100, used in these examinations, allows easy processing of the obtained digital images, which greatly expands the capabilities of basic metallographic analysis. [ABSTRACT FROM AUTHOR]

Using electron beam surfacing, the specimens of products of titanium alloy of various shapes using the wire of grade Ti6Al4V were produced. In the deposited layers no defects were detected. In the course of the work, the investigations of microstructure, phase composition and mechanical properties of the specimens were carried out. For the weld metal, the structure consisting mainly of lamellar-acicular ɑ'-phase is typical. The structure contains a small amount of β-phase, which lies in the form of thin layers between the acicular precipitations of ɑ'-phase. It is not detected using the optical microscope, however can be detected applying electron microscopy and X-ray examinations. The microstructure of the deposited metal is mostly equilibrium and granular, gradient in sizes and microhardness. The microhardness of the boundary zones diff ers from the microhardness of the grain matrix, which may be associated with the diff erence in the content of alloying elements. Towards the top of the built specimen, the hardness decreases slightly. [ABSTRACT FROM AUTHOR]

On the basis of small-sized equipment SV-212M for electron beam welding, a mock-up of additive technological equipment was created to reproduce the process of manufacturing parts according to set shape and properties, applying the method of layer-by-layer surfacing with the use of metal powder materials. A hardware and software platform for the control of equipment was developed, which was integrated into additive technological equipment. The platform consists of hardware controller, which was developed on the basis of the industrial controller cRIO-9039 produced by the company National Instruments (USA) and software for 3D printing. On the created equipment, a test specimen of the product of a set shape with the following geometric dimensions: outer diameter - 85 mm, inner diameter - 55 mm, height - 35 mm was produced. For manufacturing, the powder of VT-20 titanium of the domestic company «Ti- Technology» was used. Metallographic examinations of the specimen were carried out. It was established that the surfacing structure in the body of crystallites mainly has a branchy α’-phase and a small amount of β-phase, which is characteristic of cast titanium alloy VT-20. The grain boundaries are pure, without inclusions. Parts of the specimen are without pores, which evidences about a complete penetration of the powder layer in the process of 3D printing. The hardness of the metal in all the areas is not significantly different and is in the range from HV 3960 to HV 4150 MPa. According to the results of investigations the conclusions were made. [ABSTRACT FROM AUTHOR]