Molecular dynamics simulation studies on mechanical properties of standalone ligaments and networking nodes, a connection to nanoporous material

Abstract

Structurally, nanoporous (NP) materials can be regarded as a network of interconnected nanowires. In this study, molecular dynamics simulations are employed to investigate the deformation behavior of individual ligaments and isolated three-fold nodes, which are the two main structural components in NP materials. The shear strain tensor analysis is used to quantitatively differentiate deformation mechanisms accommodating strain among structures and capture onset of necking during stretching. Ligaments and nodes behave differently in both elastic regime and plastic regime. Our results suggest that node structure is brittle with low stiffness and yield strength, similar to NP structure, while ligament structure is ductile and exhibits high stiffness and yield strength. In isolated three-fold nodes and NP network structure, we observed similar deformation behavior exists; formation of pyramidal shape defects consisted of twinning partials and Shockley partials on different {111} planes at node region. The similarity of mechanical properties and deformation behavior between node structure and NP structure indicates that the role of node components is substantially significant in controlling structure–property relationships of NP materials. Enhancing node components is proposed as a potential method for improving mechanical properties of NP materials.

Mechanism of coarsening and deformation behavior of nanoporous Cu with varying relative density

“…7(d). The necking to failure mode observed here is similar to that observed in single crystalline nanowires [39].…”

Stress-Assisted Structural Phase Transformation Enhances Ductility in Mo/Cu Bicontinuous Intertwined Composites

“…As technology such as in situ TEM developed quickly during the past decade, − the fundamental mechanisms of plastic deformation in nanoscale materials are revealed to be substantially different from bulk materials. − Dislocation-mediated mechanisms are mainly limited to nucleation of single-ended dislocation/twinning sources from interfaces or free surfaces, and forest dislocation dynamics are almost absent due to small volumes . Other mechanisms such as structural phase transformation in transformation-induced plasticity (TRIP) steels, − shape memory alloys, , and pseudoelastic nanostructures − under specific conditions of high temperature, large applied stresses, or constrained geometry (e.g., one-dimensional nanowires with small cross section) have also been observed in nanoscale materials.…”