Molecular Dynamics Simulation of Helium Cluster Formation in Ferrous-Chromium Alloy

Understanding helium transport and clustering is important for full understanding of fusion material degradation due to neutron irradiation. Molecular dynamics simulations are carried out to study the clustering of He in FeCr alloy. The simulations are performed for He fractions from 0.1 to 0.4 in FeCr alloy at temperatures ranging from 300 to 800 K. It is observed that a minimum of five He atoms is required to form a stable cluster at temperatures in the range 700 to 800 K. An He₅-(Fe/Cr)₂-V₂ complex is found to exist at 300 K. At higher temperatures, the cluster displaces the Fe and Cr atoms from their lattice sites, forming an He₅-V complex. The constituent element of the displaced material is then found to migrate inside the system, depending upon the conditions prevailing there.