GIANT DEFORMATION OF SOLIDS IRRADIATED WITH SWIFT HEAVY-IONS - BEHAVIOR OF AMORPHOUS CRYSTALLINE MULTILAYERS/

A peculiar manifestation of particle-solid interaction is the plastic deformation of amorphous materials irradiated with a beam of swift hea vy ions. This paper presents a study of this process on samples compos ed of a crystalline metallic layer sandwiched between two amorphous la yers. The RBS technique is used to determine the modifications of the geometry of the multilayers due to irradiation. The results show a hug e shrinkage along the beam direction of both the amorphous and crystal line layers, with a decreasing deformation rate when the amorphous/cry stalline layer thickness ratio decreases. The deformation is ascribed to the strong electronic excitation generated in the wake of the incid ent ions. The amorphous parts of the target experience the plastic def ormation phenomenon observed previously, while the crystalline layer i s subject to a severe creep driven by the expanding adjacent amorphous layers. The analysis of the results with a rheological model provides an estimate of the maximum compressive stress which stops the plastic deformation in amorphous solids.