2020/09/17 by Isabelle Mouton, Yanhong Chang, Mouton, Isabelle +11
Materials Science · Engineering · #Nuclear Materials and Properties #Fusion materials and technologies #Advanced Materials Characterization Techniques
paper · pdf · doi:10.48550/arxiv.2009.08073
The long-term safety of water-based nuclear reactors relies in part on the\nreliability of zirconium-based nuclear fuel. Yet the progressive ingress of\nhydrogen during service makes zirconium alloys subject to delayed hydride\ncracking. Here, we use a combination of electron back-scattered diffraction and\natom probe tomography to investigate specific microstructural features from the\nas-received sample and in the blocky-alpha microstructure, before and after\nelectrochemical charging with hydrogen or deuterium followed by a low\ntemperature heat treatment at 400C for 5 hours followed by furnace cooling at a\nrate of 0. 5C per min. Specimens for atom probe were prepared at cryogenic\ntemperature to avoid the formation of spurious hydrides. We report on the\ncompositional evolution of grains and grain boundaries over the course of the\nsample's thermal history, as well as the ways the growth of the hydrides\nmodifies locally the composition and the structure of the alloy. We observe a\nsignificant amount of deuterium left in the matrix, even after the slow cooling\nand growth of the hydrides. Stacking faults form ahead of the growth front and\nSn segregates at the hydride-matrix interface and on these faults. We propose\nthat this segregation may facilitate further growth of the hydride. Our\nsystematic investigation enables us discuss how the solute distribution affects\nthe evolution of the alloy's properties during its service lifetime.\n