Structure and Heat Resistance of Intermetallic Rhenium-Containing Alloy after Heat Treatment

The developed intermetallic Ni3Al compound-based alloys, known under the VKNA (ВКНА) and VIN (ВИН) brands, attract attention due to high operating temperatures --- up to 1200 °C, and relatively low density --- ~ 8 g / cm3. The first-generation intermetallic alloys such as VKNA-1V (ВКНА-1В) and VKNA-4U (ВКНА-4У) are known not to require multi-stage heat treatment. An increase in the strength characteristics caused by high requirements for the hot gas path materials also occurs due to an increase of high-melt alloying elements. Therefore, investigations in the field of temperature effects on the structure and properties of new generation intermetallic alloys become very relevant. In our research we studied the influence of heat treatment on the structural phase state of the VIN4 (ВИН4) intermetallic alloy containing rhenium. Findings show that annealing at close to solvus temperatures allows increasing the time to failure during 1100 °C stress-rupture strength tests. At the same time, during the heat treatment of the alloy with a high cooling rate, elements are redistributed with uneven allocation of phases of different morphology enriched in molybdenum and chromium, which negatively affects the results of stress- rupture strength. The research is an intermediate step in establishing patterns of influence of heat treatment parameters on intermetallic alloys depending on the degree of alloying.