Molecular dynamics simulations were used to study the clustering of vacancies in irradiated metals. The simulations were carried out by using the embedded atom method. A perfect crystal was first thermalized at 1300, 1500, 1700 or 1800K. Four triangular clusters of 10 vacancies were then introduced into (111) planes at randomly selected positions. The simulations were performed by using a very small time step, in order to observe the atomistic processes which were involved in the movement of each vacancy. It was found that the vacancy clusters moved and agglomerated while remaining individual clusters. That is, vacancies did not evaporate from one cluster and join a larger cluster. It was noted that there were 3 different processes involved in the agglomeration of vacancy clusters. One was an atom, caged within a tetrahedral vacancy structure, which moved to another lattice site. Another type was an atom which was caged within an octahedral vacancy structure and moved to another lattice site. The last was an atom which moved along a <110> row.

An MN Simulation of the Atomistic Processes of Movement and Agglomeration of Vacancy Cluster in Nickel at 1300K. R.Nishiguchi, Y.Shimomura: Materials Transactions, 2000, 41[9], 1168-71