Radiation endurance in Al2O3 nanoceramics

Abstract

The lack of suitable materials solutions stands as a major challenge for the development of advanced nuclear systems. Most issues are related to the simultaneous action of high temperatures, corrosive environments and radiation damage. Oxide nanoceramics are a promising class of materials which may benefit from the radiation tolerance of nanomaterials and the chemical compatibility of ceramics with many highly corrosive environments. Here, using thin films as a model system, we provide new insights into the radiation tolerance of oxide nanoceramics exposed to increasing damage levels at 600 °C –namely 20, 40 and 150 displacements per atom. Specifically, we investigate the evolution of the structural features, the mechanical properties, and the response to impact loading of Al2O3 thin films. Initially, the thin films contain a homogeneous dispersion of nanocrystals in an amorphous matrix. Irradiation induces crystallization of the amorphous phase, followed by grain growth. Crystallization brings along an enhancement of hardness, while grain growth induces softening according to the Hall-Petch effect. During grain growth, the excess mechanical energy is dissipated by twinning. The main energy dissipation mechanisms available upon impact loading are lattice plasticity and localized amorphization. These mechanisms are available in the irradiated material, but not in the as-deposited films.

Improved high temperature radiation damage tolerance in a three-phase ceramic with heterointerfaces

“…3 . Efficient elimination of point defects during irradiation of nanocrystalline oxides has been shown to be effective for grain sizes well below 100 nm for a range of experimental conditions at relatively low temperatures 2 – 4 . In addition, near the grain boundaries of irradiated ceramics at high temperatures denuded zones have been observed that range from 20 nm to 1 μm, depending on the irradiation condition and the material 18 – 20 .…”

“…A fine grain size is expected to increase the radiation damage tolerance in polycrystalline materials since point defects generated during irradiation have only a short diffusion distance to reach grain boundaries that serve as sinks. Improved radiation damage tolerance has been demonstrated in a variety of nanocrystalline ceramics 2 – 4 , 7 , 11 . However, diffusion of interstitials to grain boundaries requires the grain sizes to be below 20 nm in single-phase ceramics at low temperatures.…”

Innovative Gen-II/III and research reactors' fuels and materials

“…IL TROVATORE is an international collaboration that combines academic excellence with strong industrial support, boasting 30 beneficiaries across 3 continents (i.e., 28 beneficiaries from Europe, 1 from the USA, and 1 from Japan). IL TROVATORE focuses primarily on the following innovative accident tolerant fuel (ATF) cladding material concepts: (a) SiC/SiC composite clads (different designs) [2,3], (b) MAX phase-coated [4] and (c) oxidecoated commercial zircaloy clads [5], (d) Gepulste Elek-tronenStrahl Anlage (GESA) surface-modified commercial zircaloy clads [6], and (e) oxide-dispersed-strengthened (ODS) FeCrAl alloy clads [7]. Figure 1 shows images associated with the innovative cladding materials which are proposed and fabricated within the Project IL TROVATORE; more details on these material concepts have been presented elsewhere [8].…”

Research and Development Roadmaps for Liquid Metal Cooled Fast Reactors – Draft for Public Comment

“…Coatings on the cladding surface, such as Al2O3 through Pulsed Laser Deposition, can be an alternative solution to mitigate corrosion problems, especially in consideration of the excellent behavior demonstrated under irradiation, although with ions, up to 150 dpa [Garcia Ferre 2016]. However, it must be demonstrated that such a coating would be adherent to and protective for the clad or duct on which it applied.…”