Size effect and its atomistic origin on the mechanical properties of open-cell nanoporous amorphous alloy

Nanoporous amorphous alloys exhibit outstanding mechanical properties, including enhanced ductility, high strength-to-density ratio, and exceptional toughness. In this paper, atomistic models of nanoporous CuZr amorphous alloys (NP–CuZr AAs) with self-similar microstructures but varying ligament sizes are constructed. Molecular dynamics simulations are employed to examine the effects of ligament size on their mechanical properties. The yield strength, yield strain, and Young's modulus are found to be higher under tension than under compression. This tension-compression asymmetry stems from the surface effect, and it becomes more pronounced with decreasing ligament size. As the ligament size increases, the Young's modulus and compressive yield strength increase, while the tensile yield strength and ultimate tensile strength decrease. The tensile behavior comprises linear elastic deformation, strain-hardening, and ligament decay stages. During the ligament decay deformation stage, ligament necking and fracture are more severe with larger ligament sizes, resulting in relatively lower resistance stress.