Nucleation-controlled distributed plasticity in penta-twinned silver nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Mechanical Engineering

Background:

• Silver nanowires (NWs) are crucial in nanotechnology.
• Understanding their mechanical properties, especially strength and ductility, is vital for applications.
• Size-dependent deformation mechanisms in NWs remain an active area of research.

Purpose of the Study:

• To demonstrate a unique size-dependent strain hardening mechanism in penta-twinned silver nanowires (NWs).
• To achieve high strength and ductility simultaneously in these NWs.
• To elucidate the role of twin boundaries and surface effects on deformation.

Main Methods:

• Combined experimental and computational approach.
• Investigation of penta-twinned silver nanowires (NWs) of varying sizes.
• Analysis of deformation mechanisms at the nanoscale.

Main Results:

• Thin Ag NWs deform via surface nucleation of stacking fault decahedrons (SFDs) in multiple plastic zones.
• Twin boundaries facilitate SFD chain formation, leading to local hardening and subsequent nucleation.
• Surface undulations trigger chain reactions of SFD arrays at stress concentrations.
• Thick NWs show lower flow stress and fewer plastic zones due to necking and complex dislocation structures.

Conclusions:

• A size-dependent strain hardening mechanism is identified in penta-twinned Ag NWs, enabling high strength and ductility.
• The observed mechanism is robust against defects due to surface-initiated SFD chain reactions.
• Nanowire thickness significantly influences deformation mechanisms and mechanical properties.