Dislocation structure in coarse-grained copper after ion implantation

Abstract

We have investigated the dislocation structures formed in the near surface region of ion implanted coarse-grained copper (grain size 460 μm) using transmission electron microscopy. Ti and Zr ions were implanted into copper using a vacuum arc ion source. The ion energy was about 100 keV and the applied (incident) dose was 1 × 10 17 cm −2. We find that Ti and Zr ion implantations produce a developed dislocation structure in the Cu subsurface layers. The dislocation structure changes form cell-net and cell dislocation structures at shallow depth to individual randomly distributed dislocations at greater depth. The maximum dislocation density in copper is 6.1 × 10 9 cm −2 for Ti and 11.4 × 10 9 cm −2 for Zr. The thickness of the modified copper layer with high dislocation density is up to 20 μm for Ti and 50 μm for Zr. Microhardness measurements vs. depth and dopant concentration profiles are presented. The long range effect is explained in terms of a model of static and dynamic mechanical stresses formed in the implanted surface layer.