The results of the backward isothermal extrusion process as to 258 mm-diameter titanium VT23 alloy hemisphere blank forgings having extended fitting adapters are presented. Using three blank sizes, the effect is studied of the two-junction isothermal forging parameters on the hemisphere blank forging qualities. The effect is shown of the strain extent and initial blank sizes at the first junction on the blank forging quality rating at the second junction. It is found that the required hemisphere blank forging qualities as to mechanical characteristics, macro- and microstructures, and geometries correspond to the initial 150 mm-diameter and 110 mm-high blanks being 35 % strained at the first junction. In so doing, the backward isothermal extrusion of the 258 mm-diameter hemisphere blank forgings increases an ultimate strength of 1079 up to 1270 MPa, an impact toughness of 20 up to 25 J/cm2 as well as decreases a blank forging of 11.5 up to 8.9 kg compared to standard similar hot die-forged blanks.

Research and development results of backward isometric extrusion technology applied for сups forgings made of high-strength titanium VТ23 alloy are presented. Stages of technology production namely from the drafting of forging and the forging tooling to the production of maintenance and forgings test batches and characterization of their properties are considered.

This paper addresses the effect of hot isostatic pressing (HIP) and heat treatment (HT) on the residual porosity, microstructure, and mechanical properties of the heat-resistant EP741NP nickel alloy produced by laser powder bed fusion (LPBF). The structural evolution was studied by X-ray powder diffraction, optical microscopy, as well as scanning and transmission electron microscopy. Special focus was placed on fine structure investigation to identify strengthening phases and alloying elements distribution. It was found that different Laves phases were formed in the interdendritic space during LPBF and were transformed to MC and M(23)C6 carbide phases during the subsequent HIP and HT. HIP resulted in healing of microcracks and large pores, as well as segregation of the strengthening gamma-phase consisting of irregularly shaped inclusions of heterogeneous size. Heat treatment led to a higher content of the gamma-phase, its refinement and more homogeneous distribution within the alloy matrix. Exposure to HIP and HT gave rise to a material characterized by ultimate tensile strength sigma similar to 1350 MPa and ductility delta similar to 12% (its strength characteristics were more than 30% superior to those of the LPBF samples).

The structure of EP741NP alloy samples produced by selective laser melting (SLM) in various technological modes, with various types of defects (the volume fraction of which varies from 0.31 to 0.65%), is investigated using optical and scanning electron microscopy; the mechanical characteristics of the samples are determined by tensile tests. All investigated SLM samples are typified by low strength characteristics, which is associated with the formation of a metastable single-phase structure, as well as with the presence of structural defects in the form of cracks. To improve the mechanical properties, the postprocessing of various types is carried out, including hot isostatic pressing (HIP); the heat treatment (HT) of the “quenching + ageing” type; and complex processing, which combines HIP and HT. According to the research results, the influence of various types of postprocessing on the microstructure and properties of SLM samples is determined. It is established that the use of HIP contributes to a decrease in porosity down to 0.04 vol %, the recrystallization of the structure, and the precipitation of the strengthening intermetallic phase based on Ni3Al (γ' phase) in the form of large particles of different sizes that create agglomerates. HT leads to the recrystallization of the structure and the precipitation of the finely dispersed γ' phase, which is uniformly distributed in the alloy matrix. In this case, the strength characteristics of the samples after HIP and HT are approximately on the same level (σu ~ 1250–1290 MPa); however, the ductility of the samples after HT is significantly lower, which is associated with the retention of defects in the structure in the form of cracks and large pores. The maximum increase in mechanical characteristics (σu of up to 1460 MPa and δ of up to 21.3%) is recorded during the complex postprocessing (HIP + HT), which ensures the elimination of defects and the formation of an optimal alloy structure.

The technology for producing granules of various fractions from electrodes for centrifugal spraying, which are fabricated according to two technological schemes, is analyzed. The technological schemes considered in the article make it possible to produce granules with a low oxygen content from electrodes of a granular KhN51KVMTYuB (EP741NP) nickel superalloy, and the appearance of the granules does not differ radically from that of the granules produced from the electrodes made by turning a VAR ingot.

Implementing the latest additive technologies such as selective laser melting (SLM) and electron-beam melting (EBM), as well as direct metal laser sintering (DMLS) requires source materials (powders, or microgranules) of a specified chemical or granulometric composition. This paper describes a brand new technological process of obtaining composite microgranules that consists of three main stages: (1) synthesizing a NiAl-based intermetallic alloy of a specified chemical composition by centrifugal SHS metallurgy, (2) single-stage metallurgic processing (vacuum induction melting or inert-medium melting) of synthesized SHS materials (cast-charge materials, CCM) to be subsequently cast in a specially prepared steel tube for crystallizing; (3) centrifugal atomization (PREP) of the obtained steel-shell electrodes to make spherical composite microgranules. A NiAl-Cr-Co-Hf nickel-aluminide-based multi-component cast alloy was synthesized by that technology. We obtained the kinematic-viscosity dependency for this SHS alloy. Series of studies was conducted to optimize the vacuum-induction melting, and the melt was cast in a specially prepared steel crystallizer. We thus melted a double-layer electrode for plasma-rotating electrode process. The electrode was atomized to produce spherical microgranules and to study their morphology.

OJSC «Kompozit» traces its history back to the Central Research Institute of Materials Science (CRIMS) and successfully acts as a leading material science institute in the rocket and space industry up to the present day. The enterprise uses and improves state-of-theart technologies, and creates a variety of new metal, non-metallic, composite and ceramic materials. This article provides an overview of powder sector development from the metallurgy of granules to additive technologies and shows the participation of MISIS graduates. The experience of OJSC «Kompozit» in the manufacturing of parts by selective electron beam melting (SEBM) of home-made VT6S titanium alloy powders. Initial powders are obtained by plasma centrifugal spraying of the bar stock. It is shown that the powders feature an ideal spherical shape, low defect rate, high processability and fully meet the process requirements. The microstructure and properties of samples and parts obtained by the SEBM are studied.

Niobium and niobium thin films are widely used in various fields of modern science and technology: in the electronics industry, in a nuclear medical imaging technique, in the information technology, in superconducting cavities technology etc. The grain size of thin niobium films depends on its thickness and the film’s stoichiometry can be varied as a function of thickness. Thus the problem of thickness control has a great practical importance in all fields of niobium films application. The focus of this study was to perform an experimental calibration of STC–2000A deposition controller for niobium target on ADVAVAC VSM–200 setup and to conduct a grain size, roughness and stoichiometry research by scanning electron microscopy, X–ray diffraction and laser interference microscopy of niobium films produced by RF magnetron sputtering with the thickness range from 200 nm to 400 nm and 50 nm step.

A high-speed method of powder production is analyzed. X-ray, chemical, and granulometric analysis indicates that the particle size of the powder obtained depends on the grinding conditions. The properties of the powder are basically the same as those of the initial sample.

Multicomponent (Cr, Fe, Co, Ni, Al, Ti, and Nb) powder alloys prepared by milling five- to seven-component equiatomic mixtures of elemental powders in a Fritsch (P-7) planetary mill have been characterized by differential thermal analysis and X-ray diffraction. The results demonstrate that, if the starting mixture contains Al, the BCC solid solution formed as a result of the milling undergoes heating-induced CsCl-type ordering (β-phase). If not only Al but also Ti are present in the starting mixture, further heating causes the β-phase to convert to an L21 phase with the composition (Ni,Co)TiAl. The elements Cr and Fe form a tetragonal σ-phase. The presence of Nb in the starting mixture suppresses the formation of the σ- phase and favors the formation of a hexagonal Laves phase of complex composition: (Fe,Co)CrNb.

An alternative technology is proposed for the production of NiAl–Co–Cr–Hf–Al 2 O 3 alloy rods. It includes the fabrication of a powder by mechanochemical synthesis (MCS) followed by hot isostatic pressing in forming tool. The processes of MCS of the intermetallic alloy in a planetary mill and an attritor are studied. The products of synthesis in various mixers are compared. The microstructure and the properties of compacted samples are studied: their ultimate compressive strength is 1390–1480 MPa at a plasticity of 8.5–8.8%. Spherical granules with a target size of 20–200 μm are fabricated by plasma centrifugal spraying of the rod workpiece formed by the proposed technology.

The processes of mutual element diffusion in coating and matrix are the one of significant factors affecting the service life of critical components and assemblies, including products with coatings. These processes render a direct influence on the corrosion resistance and wear of parts, operating at high temperatures in aggressive environments, such as the petrochemical industry. The paper proposes a method for calculating the concentrational distribution of elements in matrix and its coating at high temperature gradients and internal stresses. Concentrational mechanism of diffusion and thermal diffusion by the vacancy mechanism are the dominant mass transfer processes of the coating elements at the binary ‘steel–coating’ system heated to 1173K (1073–1173K is the temperature of the pyrolysis under industrial conditions). Both transfer mechanisms are directed into the matrix depth which leads to an intensive relocation of coating atoms to its internal surface layers. The focus of this study was to perform an analysis of the coating concentrational profiles, obtained on the basis of thermal diffusion and vacancy mechanisms of mass transfer taking into account internal stresses in the crystal lattice of matrix.

The paper proposes a model for longitudinal and transverse stresses simulation by multigrid technique with numerical solutions of differential equations in partial derivatives for research the processes of detachment and cracking on the surface layers of metal and alloy products. The developed model can be useful at the optimal modes selection of surface treatment with electron and ion beams radiation. Simulation shows that in order to avoid the cracks appearance on the AISI A2 steel surface radiated with 400 keV electron beam energy the maximum radiation parameters should not exceed 0.9 kA/cm2 current density and 150ns pulse duration. This investigation assesses the stress arising at the matrix depth in a perpendicular direction to the electron beam and evaluates its magnitude that may exceed the stresses occurring through the matrix depth more than twice.

This paper presents a detailed study of the formation of chromium-based alloys, Cr–Ta–W + plasticizing additives (Nb and Zr) and Cr–Ta–Si, during milling of powder mixtures in a Fritsch (P-7) planetary mill under an Ar atmosphere. It is shown that, after milling for 18 h, all the components of the starting mixtures convert into a Cr-based BCC solid solution. The powders of chromium alloys obtained in this study are readily compacted by hot isostatic pressing (HIP) under conditions typical of the processing of powders of high-temperature nickel alloys. Heating of the powders and compacts leads to the decomposition of the supersaturated solid solution and the formation of two forms of the Cr2M Laves phase with cubic crystal lattices. The formation of a mixed-phase fine microstructure in the chromium alloys after HIP suggests that the materials studied here are potentially attractive as a base of next-generation chromium-based high-temperature alloys.

NiAl-based electrodes of a required size were fabricated by combined use of centrifugal SHS casting and induction remelting in an inert atmosphere and characterized by modern analytical methods. Thus produced electrode materials exhibiting high chemical purity and low content of impurity gases (0.005 wt % O, 0.0001 wt % N) can be recommended for use in centrifugal plasma sputtering of micro granules via the plasma rotating electrode process (PREP).