Using the methods of scanning and transmission electron microscopy, the features of the structural-phase state of a vanadium alloy of the V-Cr-Ta-Zr system after a combined treatment, which consisted in cyclic alternation of thermomechanical and chemical-heat treatments, were studied. The values of yield strength and ductility of the V-Cr-Ta-Zr alloy were determined, depending on the stabilization and test temperatures. It was established that, after the combined treatment, the structural-phase state of the V-Cr-Ta-Zr alloy was composite, in which the joint implementation of dispersion and substructural strengthening ensured the formation of a gradient grain structure with a polygonal state, the elements of which were fixed by nanosized ZrO2 particles characterized by a high thermal stability. Such modification of the microstructure was accompanied by an increase in the high-temperature strength and a shift in the upper limit of the temperature stability interval towards high temperatures, of up to 900 °C. It was assumed that the polygonal state inside the grains contributed to the implementation of cooperative mechanisms of the dislocation-disclination type, which ensured the accommodation of the material in the "high-strength state" under loading.
Keywords: dispersion strengthening; internal oxidation; microhardness; microstructure; thermal stability; vanadium alloys.