First principles study on helium doping at the interface of Fe Cr alloy

Abstract: As a candidate material for fusion reactors, the main components of low activation ferrite steel (martensitic steel) are Fe and Cr. In actual working conditions, helium produced by fusion reactions will enter the material, causing microscopic defects and radiation damage, affecting the material's resistance to radiation (helium embrittlement phenomenon) and other physical properties. This article simulates the interface of Fe Cr alloy, the main material of the reactor, through first principles calculations. He atoms are doped at different substitution and interstitial sites, and the formation energy of each structure is calculated after optimizing its structure. The stability of He atoms at different positions on the Fe Cr interface is obtained. At the same time, by calculating the volume, it was found that He would cause significant lattice distortion at the Fe octahedral gap near the interface. Based on the analysis of electronic density of states, it is inferred that this is the result of the hybridization of He, Fe, and Cr atoms at specific positions, provide a theoretical basis for the next research on the microscopic defects and physical and chemical properties of nuclear grade stainless steel.