Corrosion resistance of vanadium alloys under the action of inert gas impurities

Methods of improving the high-tempera ture strength and corrosion resistance of vanadium and certain alloys used in reactors

“…8). This is attributable to the features of gas exchange between the liquid and solid phases [11,20,23,42,46], different diffusion mobilities and directions of fluxes of its components, and changes in the chemical composition of the alloys and interstitial impurities ( Table 6). …”

“…Durometric measurements performed after long-term soaking in vacuum [30] and helium [23] revealed regular changes in microhardness across the cross section of the unalloyed metal and some alloys. This fact, along with the data of chemical analysis (Table 6) [46], confirm the fact of gas exchange in the system "structural metal-reactor medium."…”

“…According to thermodynamic calculations [23], the fusible oxide V 2 05 must be unstable at temperatures above 820 K in a helium heat-transport medium (the partial pressure of oxygen, at which V 2 05 forms, is lower than the equilibrium partial pressure of oxygen in a gaseous mixture). Under these conditions, lower vanadium oxides V 2 04, V 2 03, VO and vanadium monocarbide are more stable.…”

“…I -uniform across the cross section, II -with an increase in the hardness at the edge, I I I -with a decrease in the hardness at the edge, IV -intermediate, and V -with extrema [23,30,[43][44]. According to the data of microstructural and x-ray analyses, the type of microhardess profiles is governed by the nature of the metal and the medium and by operating parameters.…”

“…2) for specimens tested by temporary bending in lithium and sodium melts leached with lead (for comparison) [18,19] and isothermally soaked in these media [20,21], dynamic vacuum [22], and helium as a heat-transport medium [23] as well as for specimens-witnesses (that are in the medium but not deformed) showed that the influence of reactor media is quantitatively regulated by the test temperature, nature of the medium, duration of the interaction, and changes in the mechanical properties of the metal after isothermal soaking and in the process of deformation in the whole temperature range under investigation (Fig. 2a, c, d).…”