Advanced nuclear reactor designs call for materials that can sustain very high dose (300~400 dpa) environment. Designing defect-self-healing structures/materials in atomic levels that work effectively in such an extreme becomes an ultimate goal for materials scientists and radiation damage experts. Nanostructured materials show good promising signs in fulfilling this endeavor. This talk will first briefly overview ion irradiation and response of nanostructured materials that Ion Beam Materials Laboratory has involved in Los Alamos, and then present in more detail the recent results on one of such materials - nanoporous structures.

In a recent paper we showed using computer simulations that length and time scales determine the overall behavior of nanoporous materials under irradiation [1]. These scale lengths are the size of the ligament in the foam compared to the collision cascade size and the characteristic time scale for defect annihilation relative to irradiation dose rate. The model defines a window of radiation endurance and predicts conditions for nanoporous gold (np-Au) to be radiation resistant. Ion irradiation experiments were recently performed to help understand defect evolution behavior in such a material [2]. The np-Au structure with a ligament size of 20-30 nm was irradiated with 400 keV Ne⁺⁺ ions to a total dose of 1 dpa under different dose-rates. The stacking-fault-tetrahedra (SFTs) were observed under high dose-rate irradiations at room temperature but not cryogenic temperature. The results are discussed in the frame of the model predictions.

[1] E. M. Bringa et al. “Are Nanoporous Materials Radiation Resistant?” Nano Letters 12 (2012) 3351.

[2] E.G. Fu et al. “Surface effects on the radiation response of nanoporous Au foams”, Appl. Phys. Lett., 2012 (in press).