title: Impact of Joule heating, roughness, and contaminants on the relative hardness of polycrystalline gold.
abstract: Asperities play a central role in the mechanical and electrical properties of contacting surfaces. Changes in trends of uniaxial compression of an asperity tip in contact with a polycrystalline substrate as a function of substrate geometry, compressive stress and applied voltage are investigated here by implementation of a coupled continuum and atomistic approach. Surprisingly, an unmodified Au polycrystalline substrate is found to be softer than one containing a void for conditions of high stress and an applied voltage of 0.2 V. This is explained in terms of the temperature distribution and weakening of Au as a function of temperature. The findings in this communication are important to the design of materials for electrical contacts because applied conditions may play a role in reversing relative hardness of the materials for conditions experienced during operation.
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Freeze
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: Ji
authors.forename: Angus I
authors.initials: AI
authors.lastname: Kingon
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Irving