Deformation mechanisms of irradiated metallic nanofoams
LA Zepeda-Ruiz and E Martinez and M Caro and EG Fu and A Caro, APPLIED PHYSICS LETTERS, 103, 031909 (2013).
It was recently proposed that within a particular window in the parameter space of temperature, ion energy, dose rate, and filament diameter, nanoscale metallic foams could show radiation tolerance Bringa et al., Nano Lett. 12, 3351 (2012). Outside this window, damage appears in the form of vacancy-related stacking fault tetrahedra (SFT), with no effects due to interstitials Fu et al., Appl. Phys. Lett. 101, 191607 (2012). These SFT could be natural sources of dislocations within the ligaments composing the foam and determine their mechanical response. We employ molecular dynamics simulations of cylindrical ligaments containing an SFT to obtain an atomic-level picture of their deformation behavior under compression. We find that plastic deformation originates at the edges of the SFT, at lower stress than needed to create dislocations at the surface. Our results predict that nanoscale foams soften under irradiation, a prediction not yet tested experimentally. (C) 2013 AIP Publishing LLC.
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