Self healing of radiation-induced damage in Fe-Au and Fe-Cu alloys: Combining positron annihilation spectroscopy with TEM and ab initio calculations
Abstrakt
Self healing of early stage radiation damage by site selective solute segregation is a promising approach to extend the lifetime of nuclear reactor components. In the present study, the creation and autonomous healing of irradiation-induced damage is investigated in pure Fe and high purity Fe-Au and Fe-Cu model alloys.
To create radiation damage samples are irradiated at 550 degrees C by 120 keV He+ ions with fluences of 5.0 x 10(15), 1.0 x 10(16) and 5.0 x 10(16) ions/cm(2). The observed increase in the S and W parameters determined in the variable energy positron annihilation spectroscopy measurements indicates the formation of vacancy-like defects, precipitates and vacancy-solute complexes.
The presence of substitutionally dissolved Au is found to reduce the formation of radiation defects more efficiently than solute Cu. Site-specific Au precipitation at defect sites is indicated, which results in damage healing with a reduced swelling, whereas Cu precipitates and radiation damage only show weak interaction.
Ab initio calculations show that the binding energies of Au solutes to vacancy clusters (Au-V-n) are significantly larger than those of Cu solutes (Cu-V-n) whereas the binding energies of helium filled vacancy clusters Au-HenVn and Cu-HenVn are comparable. (C) 2019 Elsevier B.V. All rights reserved.