Kinetika vysokotemperaturnoy nitridizatsii splavov na osnove Zr-U

Abstract

The kinetic patterns of nitride formation have been established and the sequence of structural transformations characterizing high-temperature (at 1900 °C) nitridation of Zr-U alloys containing 2 and 5 wt.% U in the range from 3.5 to 60 minutes is presented. During high-temperature saturation with nitrogen for each composition, the solid solution (Zr,U) decomposes with the formation of composite structures ZrN-(ZrN1-n/UxEy/U)-ZrN (where E is O, N; n, x, y are stoichiometric coefficients ). During the decomposition of the solid solution, zirconium nitride is formed and a phase of metallic uranium is released, which accumulates impurities contained in the initial solid solution in the central part of the sample. Kinetic curves for a temperature of 1900 °C are approximated by an exponential law and correspond to the nitridation of zirconium. The nitridation rate of the (Zr,U) solid solution increases with increasing uranium content. To complete the formation process of a compact nitride solid solution of (Zr,U)N of stoichiometric composition, it is necessary to increase the temperature and increase the reaction duration.