Tension-compression asymmetry in plasticity of nanoporous gold

Abstract

Mechanical behavior of nanoporous gold (np-Au) has been extensively studied by nanoindentation test, but systemic analysis on the deformation of np-Au in both tension and compression is not fully carried out. In this study, we investigated mechanical behavior of np-Au in tension and compression. By preparing micro-scale samples without grain boundaries and cracks, we could focus on the mechanical properties only. Three np-Au samples were prepared and the mechanical tests were performed using in-situ push-to-pull (P-to-P) devices for tensile testing and with the nanoindenter for compressive testing. We found two significant things related with tension-compression asymmetry; (1) the tensile yield strengths are higher than the compressive yield strengths and (2) the size effect exponent n in σy ∝ dL-n where σy is the yield strength and dL is average ligament size is greater in compression. We discuss the effect of loading mode on deformation and size effect in strength.