The origin of the brittle-to-ductile transition, experimentally observed in amorphous silica nanofibers as the sample size is reduced, is still debated. Here we investigate the issue by extensive molecular dynamics simulations at low and room temperatures for a broad range of sample sizes, with open and periodic boundary conditions. Our results show that small sample-size enhanced ductility is primarily due to diffuse damage accumulation, that for larger samples leads to brittle catastrophic failure. Surface effects such as boundary fluidization contribute to ductility at room temperature by promoting necking, but are not the main driver of the transition. Our results suggest that the experimentally observed size-induced ductility of silica nanofibers is a manifestation of finite-size criticality, as expected in general for quasi-brittle disordered networks.

Damage accumulation in silica glass nanofibers / S. Bonfanti, E. Ferrero, A. Sellerio, R. Guerra, S. Zapperi. - In: NANO LETTERS. - ISSN 1530-6984. - 18:7(2018 Jul 11), pp. 4100-4106.

Damage accumulation in silica glass nanofibers

S. Bonfanti
Primo
;
E. Ferrero
Secondo
;
A. Sellerio;R. Guerra
Penultimo
;
S. Zapperi
Ultimo
2018

Abstract

The origin of the brittle-to-ductile transition, experimentally observed in amorphous silica nanofibers as the sample size is reduced, is still debated. Here we investigate the issue by extensive molecular dynamics simulations at low and room temperatures for a broad range of sample sizes, with open and periodic boundary conditions. Our results show that small sample-size enhanced ductility is primarily due to diffuse damage accumulation, that for larger samples leads to brittle catastrophic failure. Surface effects such as boundary fluidization contribute to ductility at room temperature by promoting necking, but are not the main driver of the transition. Our results suggest that the experimentally observed size-induced ductility of silica nanofibers is a manifestation of finite-size criticality, as expected in general for quasi-brittle disordered networks.
silica; ductility; fracture; nanofibers; nanowires; bioengineering; chemistry (all); materials science (all); condensed matter physics; mechanical engineering
Settore FIS/03 - Fisica della Materia
Size effects in fracture and plasticity
1-giu-2018
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/579967
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