Size dependence of effective Young’s modulus of nanoporous gold

Nanoporous gold (NPG) is a brittle, three-dimensional, random structure of Au with nanometer scale open porosity that is made by dealloying Au∕Ag alloys in acid. In this work, Young’s modulus of NPG with controlled porosity variation between 3 and 40nm is determined by mechanical testing of ∼100nm thick, free standing, large-grained, stress-free films of NPG using a buckling-based method [C. Stafford et al., Nat. Mater. 3, 545 (2005)]. Results showing a dramatic rise in the effective Young’s modulus of NPG with decreasing ligament size, especially below 10nm are presented, and possible reasons for this behavior are discussed.