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Wear-resistant materials containing tungsten carbides are used to improve the performance of various products. This work presents generalized results of investigations on producing wear-resistant layers of abrasion-resistant materials deposited on super hard VK10 material and 30Kh steel. The results of metallographic investigations and local micro-X-Ray spectral analysis to determine the chemical heterogeneity and microstructure of abrasion-resistant materials based on: nickel TeroCoteR 7888 T (Castolin Company); iron Diamax M (Castolin Company; iron – tungsten carbide strip of AN LZ-11-7 grade (Ukraine) in as-delivered condition and after deposition on the base material are given. Chemical composition of individual phases was determined, and it was shown that the main abrasion-resistant phase of these materials (tungsten carbide) is characterized by different morphology and different dimensions. Wear-resistant material of TeroCoteR 7888 T grade (Ni–Cr–Fe–Si) in the form of flexible wire consists (before deposition) of a nickel core, coated by a composite material, containing a large amount of tungsten carbides of a polyhedral shape. The interface of base metal – abrasion-resistant deposited material, which forms during deposition on the base metal, was studied, and it was shown that after deposition the tungsten carbides are chaotically distributed in the nickel matrix, forming a heterogeneous alloy. Ref. 16, Tabl. 4, Fig. 5. [ABSTRACT FROM AUTHOR]

The results of complex studies on the brazing filler metal of the Cu–Mn–Co system alloyed with iron in the range of 1…5 wt. % are presented. The melting point was determined through calculation, and it was shown that increasing the concentration of iron from 1 to 5 wt. % leads to a slight (from 912 to 923 °C) increase in the temperature of the solidus and a significant increase in the temperature of the liquidus (from 931 to 1027 °C). At the same time, the melting temperature range expands to 104 °C. The results of experimental studies on the spread of brazing filler metal on Kovar and corrosion-resistant steel have established that an increase in the iron concentration up to 5 % contributes not only to an increase in the temperature of the liquidus but also to an increase in the spread area, which is due to the melting temperature of a copper-based solid solution. Local micro-X-ray spectral analysis established a discrete distribution of constituent elements and showed that the brazing filler metal, after spreading, contains two solid solutions: copper-based and manganese-based. The research results on the Kovar-corrosion-resistant steel brazed joints have demonstrated that the addition of iron to the Cu–Mn–Co–Fe alloy leads to an increase in microhardness and shear strength. [ABSTRACT FROM AUTHOR]

The paper gives the results of investigations on fluxless brazing of АD1М, AMts (Al-Mn), AD31 (Al-Mg-Si) aluminium alloys (Al-Mg-Si) with application of Al-25Ge-5Si-5Cu-1.5Mn-0.15Ti brazing filler metal at the temperature of 550 ± 5 °С in the atmosphere of high-purity nitrogen. The results of high-temperature differential thermal analysis were used to determine the solidus and liquidus temperatures of the brazing filler metal. Thermal effects on the derived thermal curve are indicative of the presence of three phases, which correlates with the results of X-ray microprobe analysis. It is shown that the brazing filler metal structure in the initial state is formed by two solid solutions, based on α-Al and β-GeSi and eutectics. Mechanical testing revealed that the short-term strength of the brazed joints is higher than that of the base metal, and fracture occurs in AD1M alloy. Application of steplike cooling of AD31 alloy brazed joint with soaking at the temperature of 500 C promotes increase of shear strength from 84 to 102 MPa. 42 Ref., 1 Tabl., 7 Fig. [ABSTRACT FROM AUTHOR]

Shape-memory alloys are becoming ever wider applied in different industries, in particular in aerospace, medical, automotive sectors and in consumer electronics manufacturing. Application of these materials as hybrid structure elements is a promising direction when creating products with a unique set of properties: high mechanical values, superplasticity, damping ability, higher wear resistance and thermomechanical memory. Production of nitinol permanent joints by welding leads to formation brittle phases of Ti2Ni type, which degrade the product quality. This review discusses the possibility of producing high-strength permanent joints of nitinol with nitinol and with other alloys by brazing. The main advantage, compared to other methods, is the fact that base metals do not melt, and some structural transformations can be avoided. At nitinol brazing in ambient air, brazing filler metals of Ag–Cu–Zn-Sn–Ni system haven proven themselves well, using 25AgCl–25KF–50LiCI flux. We should specially mention application of silver brazing filler metals and interlayers from pure metals, for instance, niobium, providing a strong metallurgical bond with the base metal. At brazing temperature of 1180 °С an alloy based on quasibinary NiTi–Nb eutectic system is formed, ensuring the reliability of brazed elements when creating prototypes of superplastic honeycomb shapes from titanium nickelide. 32 Ref., 4 Tabl., 8 Fig. [ABSTRACT FROM AUTHOR]

At brazing dissimilar joints of AD1 aluminium to VT1-0 titanium at the temperature of 605…610 °С by Al–12Si brazing filler metal in argon application of reactive flux of KAlF4 –10K2 SiF6 system with additives of CoF2, K2 ZrF6 compounds, promotes production of a sound joint due to formation of a low-melting alloy of Al-Si system on the contact surface. The low-melting alloy of Al-Si system newly-formed at reactive-flux brazing can independently fulfill the function of brazing filler metal at formation of a dissimilar metal joint. Cobalt reduced from the flux has little influence on weld structure and joint strength. At application of Al–12Si brazing filler metal and reactive flux of KAlF4 –10K2 SiF6–5K2 ZrF6 system, which contains potassium-zirconium fluoride (K2 ZrF6 ), a certain refinement of the structure (dendrites of aluminium-based solid solution) is observed from the aluminium side that promotes an improvement of shear strength of aluminium-titanium brazed joints. 33 Ref., 3 Tabl., 8 Fig. [ABSTRACT FROM AUTHOR]

The work presents the results of metallographic and X-ray microspectral studies of molybdenum-Kovar overlap joints, which were produced by vacuum brazing with application of brazing filler metal based on Cu-Mn-Co system. The influence of soaking at brazing temperature on brazed seam structure formation was studied. Local X-ray microspectral analysis was used to determine the number of structural components of the brazed seam: copper-based solid solution, individual iron-based grains, reaction layer in the form of a continuous band on molybdenum - brazing filler metal interface. It was found that longer soaking at the brazing temperature promotes an increase of the reaction layer width from 1 to 3 ~m and leads to formation of a faceted morphology from the brazed seam side and to microcracks initiation in it, but it does not affect molybdenum concentration, which at different soaking (1…15 min.) is in the range of 55.81…59.05 wt. %. In the solid solution (matrix) manganese concentration decreases with longer soaking, copper concentration rises, but the quantity of iron practically does not change, and it is in the range of 4.52… 4.95 wt. %. In single grains of the dark phase, observed near the interface with Kovar, longer soaking promotes an increase of iron and nickel concentration and lowering of manganese and copper content. [ABSTRACT FROM AUTHOR]

Modern brazing filler metals for brazing high-temperature nickel alloys are complex alloys, where the components should provide the required level of strength, high-temperature resistance, high-temperature corrosion resistance and other service properties of brazed joints. However, establishing the optimum composition to obtain the desired set of properties is a non-trivial task, requiring considerable investment of time and money. The work is a study of applicability of the method of mathematical modeling of thermodynamic processes (CALPHAD) during development of multicomponent brazing filler metals for brazing high-temperature nickel alloys. During performance of investigations, using CALPHAD computational procedure, melting temperature ranges were determined for a number of alloys of Ni–Cr–Co–Al–(Ме)–Ta system. Calculated data were obtained on the influence of adhesion-active elements of group IV and V of the periodic table on liquidus temperature and phase composition of the basic nickel alloy. In particular, their impact on the quantity and thermal stability of γ'-phase and σ-phase was determined. Thermodynamic calculated data, obtained with application of mathematical modeling method, were used during development and investigation of a number of promising brazing filler metals for brazing high-temperature nickel alloys, including single-crystal high-temperature nickel alloy ZhS-32VI. 21 Ref., 8 Fig. [ABSTRACT FROM AUTHOR]

Plasma brazing of steels is performed using brazing filler metals having liquidus temperature above 1000 °C. This work shows the possibility of lowering the brazing temperature by applying brazing filler metals having a lower melting temperature. The method of high-temperature differential thermal analysis was used to establish the influence of manganese, nickel and silicon on solidus and liquidus temperatures of experimental alloys of Cu–Mn–Ni–Si system. Empirical data and mathematical processing methods were applied to determine the influence of chemical elements on calculated coefficients of the impact of alloying elements on solidus and liquidus temperatures of alloys of Cu–Mn–Ni–Si system that promotes lowering of melting temperature. The influence of nickel and silicon content at fixed quantity of manganese of 10 and 16 wt.% on the area of spreading over 08kp (rimmed) steel and melting temperature range was studied. Sound formation of brazed joints from 08kp alloy produced by plasma brazing with application of the studied alloys was proved experimentally. Ref. 16, Tabl. 2, Fig. 5. [ABSTRACT FROM AUTHOR]

The features of spreading of brazing filler metal of Cu-Mn-Co system over molybdenum and Kovar were established based on the performed studies. Micro X-ray spectral analysis determined that zonal crystallization of a brazing filler metal droplet on the base metal substrate occurs during spreading: pronounced areas of copper-based solid solution (Cu-12.92Mn-4.69Co) form along the outer perimeter of the droplet, and dendrites of manganese-based solid solution, characterized by a higher melting point, are crystallized in the drop central part. It has been experimentally proven that an increase in the heating temperature contributes to an increase in the spreading area of the brazing filler metal by improving the spreading of copper-based solid solution. It was found that a copper-based solid solution forms in the brazed seam of Kovar-molybdenum dissimilar joints, and a molybdenum-based reaction layer (about 1 μm wide), crystallizes at the molybdenum-brazing filler metal interface. This layer is enriched in cobalt (15.80%) and manganese (14.12%) and contains a small amount of copper (1.63%). %). As a result of mechanical tests of Kovar-molybdenum overlap joints under static loads at room temperature, destruction occurs partly along the brazed seam and partly along the base metal - molybdenum. 14 Ref., 2 Tabl., 6 Fig. [ABSTRACT FROM AUTHOR]

The results of investigations of pre‑eutectic alloys of the Cu – P – Sb system are presented. The melting temperature interval was determined using high‑temperature differential thermal analysis. It was found that antimony alloying of copper‑phosphorus pre‑eutectic alloy provides a decrease in the temperature of solidus and liquidus. On the basis of experimental and literature data, the surfaces of liquidus and solidus of ternary alloys were constructed. Using micro‑X‑ray spectral analysis, the chemical composition and a number of structural components of the Cu ‑ 6.29P ‑ 1.97Sb alloy were determined. The influence of antimony on technological and mechanical properties, as well as morphology of cast ternary pre‑eutectic copper‑phosphorous alloys is shown. 10 Ref., 2 Tabl., 6 Fig. [ABSTRACT FROM AUTHOR]

In the manufacture of thin-walled structures by welding, residual stresses appear in them, which negatively affect the geometric parameters and quality of the obtained products. The paper presents the results of evaluation of residual stresses on simulator-samples made from galvanized steel 08ps (semi-killed) after MAG welding, and plasma brazing using constant and modulated current. Lowering of residual stresses and avoidance of brazing filler metal spattering are promoted by reduction of heat input, when making permanent joints. One of the ways contributing to it, is application of plasma brazing, which provides the ability of setting the current, independently of filler material feed rate. Determination of the magnitude of residual stresses in the joints was performed by the magnetoelastic method. It is shown that in plasma brazing with constant current the dimensions of plastic deformation zone are much smaller than in MAG welding, which is associated with a decrease in the amount of thermal energy applied to the metal. Plasma brazing with constant current allows lowering residual stresses from 149, which is obtained by welding, to 119 MPa. Further decrease of residual stresses (to 85 MPa) during plasma brazing of joints of galvanized steel 08ps is possible due to the use of modulated current [ABSTRACT FROM AUTHOR]

The paper presents the results of investigations of brazed joints of 08Yu galvanized steel, produced by welding, arc and plasma brazing. It is confirmed that in the first case, spattering of the liquid pool metal, zinc evaporation and porosity formation take place. The influence of energy input on brazed seam parameters was studied in plasma brazing with application of BrKMts 3-1 brazing filler metal. It was found that increase of energy input leads to reduction of face reinforcement height, but promotes increase of the reverse reinforcement height, that requires a greater amount of brazing filler metal. It was empirically determined that energy input value in the range of 520 - 590 J/cm ensures producing butt joints of galvanized 08Yu steel with optimum size of reverse reinforcement. X-ray microprobe analysis showed that high-quality dense welds form in this mode that have the structure of copper-based solid solution with dispersed inclusions of iron-based phase, enriched in silicon. 11 Ref., 1 Tabl., 9 Fig. [ABSTRACT FROM AUTHOR]

The paper presents practical results of developments and investigations in the field of brazing various materials: aluminium, copper, high-temperature nickel and titanium alloys, as well as promising materials based on Ni3Al and TiAl intermetallics, and steels of different grades. Data on reactive-flux brazing of aluminium thin-walled structures in a controlled gas environment are given. A lot of attention is paid to producing brazed joints from dissimilar materials: Mo+C (stainless steel), W+Cu, hard alloy material (VK 20)+steel, Al+steel, etc. Effective application of the developed technologies of brazmg high-temperature nickel and titanium alloys in fabrication of critical structures for high temperature applications and results of mechanical testing of brazed joints are shown. The developed brazing filler metal and technologies of high-temperature vacuum brazmg were applied to produce joints from new generation alloys based on nickel and titanium aluminides, which have been successfully tested for long-term strength under the conditions of higher temperature and continuously applied stresses. [ABSTRACT FROM AUTHOR]

The paper presents the results of high-temperature differential thermal analysis of braze alloys based on Cu-Mn-Ni-Si system, metallographic examination of brazed joints of 08kp (boiling) steel, made with application of plasma-arc heating. It is shown that at silicon alloying of Cu-Mn-Ni system the alloy melting temperature decreases and its wetting ability increases. X-Ray microanalysis revealed that brazed seam of 08kp (boiling) steel joints consists of copper-based solid solution and dispersed precipitates of a silicon-enriched phase. An iron-based phase with higher concentration of silicon and manganese forms on braze alloy - base metal interphase as a thin band (along the brazed seam), that is indicative of appearance of silicides of a complex composition. Brazed joint strength becomes higher with increase of nickel concentration in the alloy and is equal to 367 MPa. [ABSTRACT FROM AUTHOR]