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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]

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]

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]