Effect of Carbon on Void Nucleation in Iron

The nucleation of voids in alpha iron and the influence of carbon were investigated through a combination of rate theory and nucleation theory calculations. The steady rates of void nucleation exhibit high sensitivity to carbon. Even a seemingly negligible carbon concentration, as low as a few atomic parts per million (appm), can dramatically reduce the nucleation rates and narrow the temperature window for nucleation. This study highlights the challenges in certifying and qualifying nuclear materials for use in reactor environments. It emphasizes the necessity for precise control of impurity levels during materials processing and stringent requirements for irradiation testing, which are susceptible to contamination. Furthermore, the study provides an explanation for the significant data scattering observed in void swelling behaviors as reported in the literature.