Grain boundary diffusion of Ni in ultra-fine grain copper-lead alloyproduced by equal channel angular pressing

摘要

Kinetic characteristics of internal interfaces in ultrafine grained (UFG) materialsrepresent an aspect that is central to their potential applications. Interface diffusion is stronglyaffected by ultrafine crystallinity and incorporated defects. In the present study the radiotracertechnique was applied for measuring grain boundary (GB) diffusion of Ni in UFG Cu-1 wt.%Pballoy. The UFG specimens were prepared by equal channel angular pressing at room temperature.GB diffusion was investigated at room temperature in Harrison's C kinetic regime under conditionsin which Ni diffusion - even along general high-angle GBs in pure Cu - would hardly be measurableby the mechanical sectioning (as the corresponding penetration depths would be less than 100nanometers). The present study highlights the existence of ultra-fast diffusion paths in severelydeformed material. An atypical time dependence of the room-temperature diffusion data indicates aquite involved nature of these "fast" diffusion paths in the Cu-lwt.%Pb alloy.