Temperature effect on nanoporous gold under uniaxial tension and compression

Abstract

Nanoporous gold (NP-Au) is of great interest to researchers due to its high surface area; and accordingly, the wide range of applications that the material can be utilized for especially those where high temperature is involved. Therefore, the effect of temperature on NP-Au is studied by performing Molecular Dynamics (MD) simulations at temperatures between 300 K and 700 K. Moreover, an Arrhenius type formulation is proposed to modify existing scaling laws to capture the temperature effect. Also, a series of temperature dependent modifications to an existing dislocation based constitutive model are proposed. The simulation results show that while the elastic modulus and yield stress are temperature dependent, their tension–compression asymmetries are not. Under both compression and tension, material strength is controlled by surface stresses and dislocation mobility. However, the dislocation density required to plastically deform the material is found to be completely temperature independent under tension, and becomes temperature dependent under compression once there is sufficient amount of ligaments merging and collapse.