Effects of strain and strain rate on electronic behavior of metal surfaces under bending and tension tests

Surface electronic behavior of MEMS and NEMS can be characterized using the Kelvin probe technique by measurements of work function (WF). However, the physical mechanism responsible for such electronic behavior of a surface subjected to mechanical loading has not been completely understood. In this study, changes in WF of copper and aluminum with respect to strain and strain rate under bending and tension tests were measured using a scanning Kelvin probe. The results showed that plastic strain and strain rate can decrease WF although elastic strain may lead to complex changes in WF, which can be explained well using the electrostatic energy model on dislocation density.