The effect of pore size on the deformation mechanism and mechanical properties of nanoporous Ni under tension and compression tests is studied using molecular dynamic simulations in terms of atomic trajectories, dislocation extraction algorithm, and the stress-strain curve. The simulation results show that samples have a longer elastic deformation period during tension compared to that during compression. Dislocations nucleate at pore surfaces and propagate until they are terminated by neighboring pores. Samples under tension have lower ultimate stress and higher strain at ultimate stress compared to those of samples under compression. Samples with smaller pore diameter have more transformation from face-centered cubic to hexagonal close-packed structures due to more dislocation activity. The ultimate stress of samples significantly decreases with increasing pore diameter.
Keywords: Dislocation; Molecular dynamics; Nanoporous metal; Strain; Stress.