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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 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]

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]