Self-interstitial atoms at high temperatures in dense metals

It has long been clear that vacancies are usually the most abundant defect in equilibrium in most dense, close-packed metals. However, some important effects, such as the observed deviation of the diffusion coefficient from pure Arrhenius behaviour, can not be explained by invoking only a single vacancy. The most common explanation to the deviations is that also divacancies, and possibly even trivacancies, play a significant role. However, some evidence also indicate that interstitials could play a significant role. In this article, we review some recent work and our computer simulation results on this issue. Both the reviewed work and simulations point in the direction that the interstitial could be of major importance close to the melting temperature and during rapid heating. The results also strongly support the Granato model of liquids and solids.