EVOLUTION OF THE SURFACE-RELIEF OF ANNEALED COPPER AND PALLADIUM SAMPLES UNDER LOAD

The evolution of submicrodefects on loaded Cu and Pd surfaces annealed after polishing is investigated by tunneling profilometry. The shallo west defects formed in a sample under tension appear in the form of pr ismatic indentations with a vertex angle approximate to 70 degrees. On Cu surfaces they have a depth of 15+/-3 nm and dimensions in the plan e of the surface 50x50 nm. On Pd surfaces the defects have a depth of approximate to 5 nm and dimensions in the plane of the surface 10x20 n m. The defects grow with time, attaining depths approximate to 1 mu m and areal dimensions of a few micrometers before fracture. This proces s evolves in a stop-go pattern: The defect depth remains approximately constant for a certain time, then changes suddenly, stabilizes again, changes once more, and so on. Defects of depth <100 nm are distribute d uniformly over the surface of the sample, while defects of depth gre ater than or equal to 200 nm are clustered at the boundaries of blocks . (C) 1997 American Institute of Physics.