Irradiation-induced Nb redistribution of ZrNb alloy: An APT study

We have investigated proton irradiation induced Nb redistribution in Zr-xNb alloy (x = 0.4, 0.5, 1.0) by using Scanning Transmission Electron Microscopy (STEM) and Atom Probe Tomography (APT). Initially without an irradiation effect, the Zr matrix only contains beta Nb and native Laves phase native precipitates. However, after 2 MeV proton irradiation at 350 degrees C, STEM/EDS showed irradiation induced precipitation of Nb-rich needle-like particles (up to similar to 100 nm in length) in the Zr matrix. APT also revealed that Fe- and Nb-enriched nano-clusters (less than 20 nm diameter) are present in the Zr matrix for Zr-0.5Nb and Zr-1.0Nb. Irradiation was found to reduce the matrix Nb concentration in the Zr solid solution, This reduction may contribute to the improved corrosion resistance of ZrNb alloys in the reactor environment at high burnup. (C) 2019 Elsevier B.V. All rights reserved.