Effect of Irradiation with a Pulsed Electron Beam on Chromium Diffusion in the Zr–1 wt % Nb Alloy

The diffusion of chromium from the surface was studied in a polycrystalline Zr–1 wt % Nb alloy under conditions of isothermal diffusion annealing and irradiation with a pulsed electron beam in the temperature range of (0.3–0.4) of the zirconium melting temperature using the high-frequency glow discharge optical emission spectrometry methods. It has been established that the deposition of a chromium film on the surface of the Zr–1 wt % Nb alloy by reactive magnetron sputtering of a target leads to the formation of a zone of mutual penetration of chromium and zirconium. In this case, the grain sizes, as well as the sizes and distribution of particles of the β-Nb phase in the Zr–1 wt % Nb alloy, do not change. Isothermal diffusion annealing and irradiation with a pulsed electron beam result in an increase in the width of the zone of mutual penetration of chromium and zirconium compared to the state after deposition of a chromium film on the alloy surface. A comparative assessment of the chromium diffusion parameter sD_b (s is the segregation coefficient, and D_b is the grain boundary diffusion coefficient) under conditions of isothermal diffusion annealing and irradiation with a pulsed electron beam using the Whipple-Le-Clair equation with a grain boundary width of 0.5 nm was carried out. It has been shown that under conditions of simultaneous exposure to temperature and irradiation with a pulsed electron beam the sD_b parameter increases and the activation energy of grain-boundary diffusion of chromium in the Zr–1 wt % Nb alloy decreases in the near-surface layer of the alloy.