Molecular dynamics study of displacement cascades near U/Al interface

Aluminum matrix scattered with uranium alloy powders is widely applied as nuclear fuel core. However irradiation can produce considerable swelling and porosity in the interfacial layer. To understand the underlying mechanism, molecular dynamics simulations utilizing a recently developed potential of the modified embedded-atom-method (MEAM) were conducted to investigate displacement cascades near the interface between Uranium and Aluminum. The influence of the distance of primary knock-on atoms (PICAs) to the interface on cascade damage was studied. Three different distances of PICAs with kinetic energy equal to 6 keV at Uranium lattice were selected. It is observed that the interface plays an important role for creating residual defects because it retards recovery process of displacement spikes. Further analyses show that PICAs initiated far from the interface only produce dispersed defects in low quantity, and those located near the interface tend to create more residual defects, which form voids on the interface and intrinsic interstitial clusters in the Al lattice.