Effects of elastic and plastic deformations on the electron work function of metals during bending tests

The high sensitivity of the electron work function (EWF) to surface conditions has attracted increasing interest in the application of the electron,work function (EWF) to investigate tribological phenomena using the Kelvin probing technique. In this study, the correlation between the EWF and both the elastic and plastic deformation of copper and aluminium during bending tests was investigated. It was demonstrated that, in the elastic range, tensile strain decreased the EWF, while compressive strain increased the EWF. However, in the plastic range, the EWF always decreased with plastic deformation irrespectively of whether it was tensile or compressive. The mechanism responsible for the variation in EWF with elastic and plastic deformation is analysed and discussed.