Fig. 1 Vacancy production by 3.5 MeV Fe ions in 304 SS. Recoil/damage calculations were made with Kinchin-Pease estimates

Fig. 2 Schematic diagram of S and W parameters in Doppler broadening of PAS. S represents the fractional area of the central portion of the peak, while W parameter is the fractional area of the extreme wings of the photo-peak

Fig. 3 Positron depth profiles with typical energies of 5, 10, 15, 20, 25 keV

Fig. 4 S parameter versus positron energy (mean implantation depth) plots for the irradiated and unirradiated samples

Fig. 5 W parameter versus positron energy (mean implantation depth) plots for the irradiated and unirradiated samples

Fig. 6 S parameter versus W parameter plots for the three kinds of samples

Fig. 7 Morphologies of the cross sections of the irradiated samples: a bright-field TEM image of 3.2 dpa sample, b morphology of irradiation-induced defects of 3.2 dpa sample, c bright-field TEM image of 16 dpa sample, d morphology of irradiation-induced defects of 16 dpa sample

Fig. 8 Comparison of the diameter and number density of Frank loops: a 3.2 dpa sample, b 16 dpa sample

Fig. 9 SEM micrographs of the all samples after indentation tests. Note that surface morphologies were different that grain boundaries were clear for unirradiated sample, while it became obscure for the irradiated samples

Fig. 10 Dependence of nanohardness of 304SS on the indentation depth of a unirradiated sample, b irradiated for 3.2 dpa, c irradiated for 16 dpa, d Hirr/Hunirr versus depth plot of all samples

Fig. 11 H2 versus 1/h (indentation depth) plot of the indentation results (Nix-Gao plot)