A comparison of collective dislocation motion from single slip quantitative topographic analysis during in-situ AFM room temperature tensile tests on Cu and Feα crystals

A robust topographic analysis method is presented for the slip measurements along the individual slip steps of a plastically strained single crystal in an Atomic Force Microscope (AFM). It is shown to provide access to major characteristics of the responsible collective dislocation motion. The slip measurement method is applied on a copper single crystal strained in quasi-static tension at room temperature. The single slip orientation was selected such as to allow the comparison with previous results obtained from a similar analysis of an iron single crystal. Qualitative and quantitative characteristics of slip are obtained from individual and statistical analyses of hundreds of surface slip steps - the 3D projection of slip bands - over a sample area of 100 × 100 μm2 followed up to more than ten per cent of slip. Characteristics which either differ or resemble between the two metals (details of slip kinetics, cross slip activity, band width and intensity at the surface) are discussed in reference to recent insights from dislocation dynamics and molecular dynamics results. This work attests of the efficiency of the topographic analysis method in the field of plasticity and extensions beyond simple single slip case can be envisaged.