Abstract
According to conventional steady-state rate theory predictions of displacement damage evolution in irradiated materials, the accumulation of vacancies decreases as grain size decreases. Using atomistic simulations, the authors report a transient anomaly in the dependence of radiation produced vacancy accumulation on grain size. Contrary to the conventional wisdom, the accumulation of vacancies can be higher in smaller grains than in larger grains during a transient stage. The anomaly is a result of competition between two atomic-level processes: grain boundary absorption and bulk recombination of point defects, each of which has characteristic length and time scales. A simple metal copper is used as the prototype of face-centered cubic material and electron radiation is the source of non-cascade defect production, both choices aiming at clarity for identifying physical mechanisms.
