Methods of Improving the High-Temperature Strength and Corrosion Resistance of Vanadium and Certain Alloys Used in Reactors

摘要

We present new evidence for the high-temperaturestrength of vanadium and low-alloyed (up to 15 at. percent)vanadium-based alloys under conditions of prolonged (up to5000 h) high-temperature (973-1173 K) exposure to vacuum,helium, lithium and sodium melts, modeling reactor heat-transport media (10 Pa). The kinetics of phase transformationsin alloys of the systems V-Zr-C, V-Nb-Zr-C, V-Mo-Zr-C, andV-Ti-O in the process of prolonged aging under stress isanalyzed. It is established that the process of pre-decay of asolid solution has many stages and is intensified by the action ofstresses. The corresponding isothermal diagrams of the decay ofVTsU (V-Zr-C) alloy are constructed. We giverecommendations as to the choice of alloying elements with theaim of enhancing the high-temperature strength of vanadiumand vanadium alloys used for reactors. New alloys developed onthe basis of the systems V-Ti-O, V-Nb-Zr, V-Ta-Hf, V-Cr-Sc,and V-Cr-Nd and a new method of hardening thermochemicaltreatment of vanadium-titanium alloys with the use of oxygenfrom air have found application in pilot-engineeringdevelopments for high-temperature nuclear power plants.