Characterization of Irradiation-induced Precipitates by Small Angle X-ray and Neutron Scattering Experiments Effects of Radiation on Materials

The nature of the irradiation-induced precipitates in the VVER-440-type steel 15Kh2MFA has been investigated by the combination of small angle neutron scattering and anomalous small angle X-ray scattering. By the method of contrast variation information about the chemical composition of the irradiation-induced precipitates was obtained. ASAXS experiments with variation of the X-ray energy near to the energy of the vanadium K-absorption edge prove the content of vanadium within the irradiation-induced precipitates. The scattering density of the precipitates is lower than the scattering density of the iron matrix. The chemical shift of the vanadium-K -absorption-edge and the results of the variation of the contribution of the magnetic scattering in the SANS experiment show, that vanadium does not precipitate in an elementary state. By assuming the precipitates being vanadium carbide these results can be explained in the best way.