Effects of porosity and pore microstructure on the mechanical behavior of nanoporous silver

The tensile strength of nanoporous silver (AgNPs) is investigated by experiments and molecular dynamic analysis. Effects of sintering temperature on the porosity and ultimate strength of AgNPs are studied. The tensile properties of AgNPs with different micro structures and porosities are determined. The phase field method is adopted to develop the spinodal decomposition open-cell porous microstructure. AgNPs with cube, gyroid, and sphere pores generally show brittle fracture in tension, while AgNPs with spinodal decomposition structure show brittle fracture at low porosity and ductile fracture at high porosity. The influences of porosity on the Young's modulus and ultimate strength are studied. The predicted stress-strain curves are validated by the Gibson-Ashby model and experimental data. The microstructure is investigated by common neighbor analysis and dislocation extraction algorithm. It is found that the dislocation nucleation sites are concentrated near the pore surfaces, the evolution of strain-stress curve is related to the dislocation density. Molecular dynamics simulations reveal that the uniaxial tensile deformation is accompanied by accumulation of stacking faults in ligaments, as well as the formation of Lomer-Cottrell locks at the junctions of dislocation. The influences of porosity and pore surface to the dislocation nucleation and tensile strength are discussed.