Mössbauer-spectroscopic study of the effect of He+ irradiation on model Fe-Cr alloys

Effect of 25 keV He ion irradiation on three model Fe_100−xCr_x alloys (x = 5.8, 10.75 and 15.15) was investigated by means of the conversion electron Mössbauer spectroscopy. A short-range ordering (SRO) parameter concerning a distribution of Cr atoms within the first-two neighbour shells, <α₁₂>, for all three non-irradiated samples was positive, hence indicative of ordering, yet its amplitude, hence the degree of ordering, was decreasing with x. For the samples irradiated to the dose of 1.2·10¹⁷ He+/cm² (7.5 dpa) <α₁₂ > was unaffected for x = 5.8 and 10.75 but its value was negative for x = 15.15 i.e. an irradiation-induced inversion of the SRO-parameter occurred.