Contact-Potential Changes Produced on Metal Surfaces by Tensile Stresses

Contact-potential changes produced by applied tensile stresses on a number of metal surfaces have been measured. Except at very low tensile stresses, where the results are uncertain, it is found that in the elastic region of the metal, the contact potential becomes increasingly negative with increase of tensile stress. In the plastic region of the metal, the contact potential changes sign and increases in the positive direction until rupture occurs. The experiments were carried out in an atmosphere of nitrogen.