Damage Accumulation in Silica Glass Nanofibers

Area of Science:

• Materials Science
• Nanotechnology
• Computational Physics

Background:

• The brittle-to-ductile transition in amorphous silica nanofibers with decreasing sample size is an observed phenomenon.
• The underlying mechanisms driving this size-dependent behavior remain under investigation and debate.

Purpose of the Study:

• To investigate the origin of the brittle-to-ductile transition in amorphous silica nanofibers using molecular dynamics simulations.
• To differentiate the roles of diffuse damage accumulation and surface effects in size-induced ductility.

Main Methods:

• Extensive molecular dynamics simulations were performed.
• Simulations covered a wide range of sample sizes at low and room temperatures.
• Both open and periodic boundary conditions were employed.

Main Results:

• Small sample sizes exhibit enhanced ductility primarily due to diffuse damage accumulation.
• Larger sample sizes tend towards brittle catastrophic failure.
• Surface effects like boundary fluidization contribute to room-temperature ductility by promoting necking, but are not the primary cause of the transition.

Conclusions:

• The experimentally observed size-induced ductility in silica nanofibers is a manifestation of finite-size criticality.
• Diffuse damage accumulation is the main driver of the brittle-to-ductile transition in these materials.
• The findings align with general expectations for quasi-brittle disordered networks.