CREEP OF A CRYSTALLINE METALLIC LAYER INDUCED BY GEV HEAVY-ION IRRADIATION

The atomic transport induced in amorphous systems by ion electronic en ergy loss is studied on metallic sandwiches irradiated with 500 MeV io dine ions. The sandwiches are composed of two amorphous Ni3B layers of thickness 1-1.5 mu m and of one crystalline Au or W layer of thicknes s varying from 20 to 900 nm. Rutherford backscattering experiments usi ng a 3.6 MeV He beam were performed to determine the modifications of the geometry of the sandwiches due to irradiation. A huge creep phenom enon is evidenced in the crystalline part of the sample. The amplitude of the creep depends on the nature of the crystalline layer (Au or W) and decreases with the layer thickness. This creep phenomenon is indu ced by the plastic deformation process occurring in the amorphous laye rs surrounding the crystalline one, and is due to ion electronic energ y loss.