Dislocation density transients and saturation in irradiated zirconium. (May 2023)

• Record Type: Journal Article
• Authors: Warwick, Andrew R.; Thomas, Rhys; Boleininger, M.; Koç, Ö.; Zilahi, G.; Ribárik, G.; Hegedues, Z.; Lienert, U.; Ungar, T.; Race, C.; Preuss, M.; Frankel, P.; Dudarev, S.L.
• Is Part Of: International journal of plasticity. Volume 164(2023)
• Publication Date: 2023-05
• Subjects: Zirconium -- Irradiation -- Dislocations -- Defects; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2023.103590
• Languages: English
• ISSNs: 0749-6419

Abstract

Abstract: Zirconium alloys are widely used as the fuel cladding material in pressurized water reactors, accumulating a significant population of defects and dislocations from exposure to neutrons. We present and interpret synchrotron microbeam X-ray diffraction measurements of proton-irradiated Zircaloy-4, where we identify a transient peak and the subsequent saturation of dislocation density as a function of exposure. This is explained by direct atomistic simulations showing that the observed variation of dislocation density as a function of dose is a natural result of the evolution of the dense defect and dislocation microstructure driven by the concurrent generation of defects and their subsequent stress-driven relaxation. In the dynamic equilibrium state of the material developing in the high dose limit, the defect content distribution of the population of dislocation loops, coexisting with the dislocation network, follows a power law with exponent α ≈ 2 . 2 . This corresponds to the power law exponent of β ≈ 3 . 4 for the distribution of loops as a function of their diameter that compares favourably with the experimentally measured values of β in the range 3 ≤ β ≤ 4 . Highlights: Dislocation density evolution in irradiated Zr has been predicted and measured. A transient peak and subsequent saturation in dislocation density has been observed. Dislocation loop diameters in heavily irradiated Zr are power law distributed.