Designing Brazing Filler Metal for Heat-Resistant Alloys Based on NI 3AL Intermetallide

One of the most promising structural materials in gas turbine engineering is the alloys based on an intermetallide, the type of Ni 3 Al, with an equiaxial and directional columnar structure. These materials make it possible to increase the working temperature of blades to 1,220 °C. The blades are made by the method of precise casting in a vacuum; in this case, it is necessary to technologically join the nozzle blades into blocks, to fix the signal holes in cooled blades, to correct casting defects. Welding by melting intermetallide materials, as well as other cast heat-resistant nickel alloys (HNA), does not yield positive results. Therefore, various brazing techniques are used such as TLP-Bonding (Transient Liquid Phase Bonding). Filler metals' melting point is lower than that of the main metal. The key issue related to the technology of brazing HNA, including the design of appropriate filler metals, is the improvement of the physical-mechanical and operational properties of brazed joints. This paper reports the established rational doping of a filler metal base, as well as depressants, the critical temperatures and surface properties of filler metals, their chemical composition, the structure and properties of brazed joints, the mode parameters, and brazing technology. To improve the stability of the structure and the high-temperature strength of the brazed joints, the filler metal was alloyed with rhenium and tantalum. Mechanical tests of brazed joints at 900 °C were conducted in Ukraine; at a temperature of 1,100 °C ‒ in the People's Republic of China. The test results showed that the short-term strength of alloy compounds with an equiaxial structure based on the Ni 3 Al-type intermetallide at 1,100 °C is 0.98 of the strength of the main metal. The long-lasting strength at the same temperature meets the requirements for the strength of the main metal