Anisotropic Fine-Grained Nanoporous Gold with Enhanced Flaw Tolerance

Abstract

Tough biomimetic composites were used as an inspiration for designing anisotropic fine-grained nanoporous gold (np-Au). The np-Au samples were fabricated by cyclic hot rolling and intermediate annealing. They possessed an anisotropic grain structure with an aspect ratio of 6.2 and lateral and vertical grain sizes of 4.71 and 0.76 μm, respectively. The anisotropic fine-grained np-Au showed an enhanced fracture toughness, K_Jc, of 0.310 MPa∙m^1/2 with stable crack growth. The anisotropic grain structure suppressed flaw sensitivity through crack deflection and grain boundary plasticity. These findings show that the existence of the optimal anisotropic grain structure in np-Au, as well as the grain and ligament sizes, could contribute to the enhancement of flaw tolerance.

Keywords: Rolling, Porous material, grain boundaries, Micromechanical modeling, Nanoporous gold