Smaller is tougher
- 1 March 2011
- journal article
- fracture size-effects
- Published by Taylor & Francis Ltd in Philosophical Magazine
- Vol. 91 (23), 1179-1189
- https://doi.org/10.1080/14786435.2010.487474
Abstract
“Smaller is stronger” is now a tenet generally consistent with the predominance of evidence. An equally accepted tenet is that fracture toughness almost always decreases with increasing yield strength. Can “smaller is tougher” then be consistent with these two tenets? It is taught in undergraduate engineering courses that one design parameter that allows for both increased strength and fracture toughness is reduced grain size. The present study on the very brittle semiconductor silicon proves this exception to the rule and demonstrates that smaller can be both stronger and tougher. Three nanostructures are considered theoretically and experimentally: thin films, nanospheres, and nanopillars. Using a simple work per unit fracture area approach, it is shown at small scale that toughness is inversely proportional to the square root of size. This is supported by experimental evidence from in situ electron microscopy nanoindentation at length scales of less than a micron. It is further suggested that dislocation shielding can explain both strength and toughness increases at the small scales.Keywords
This publication has 22 references indexed in Scilit:
- Brittle‐to‐Ductile Transition in Uniaxial Compression of Silicon Pillars at Room TemperatureAdvanced Functional Materials, 2009
- Scale effects for strength, ductility, and toughness in “brittle” materialsJournal of Materials Research, 2009
- Effect of temperature on fracture toughness in a single-crystal-silicon film and transition in its fracture modeJournal of Micromechanics and Microengineering, 2007
- Low‐Temperature In Situ Large‐Strain Plasticity of Silicon NanowiresAdvanced Materials, 2007
- Compressive stress effects on nanoparticle modulus and fracturePhysical Review B, 2007
- Strength and fracture of Si micropillars: A new scanning electron microscopy-based micro-compression testJournal of Materials Research, 2007
- Fracturing a nanoparticlePhilosophical Magazine, 2007
- Size-Related Plasticity Effects in AFM Silicon Cantilever TipsMRS Proceedings, 2006
- Nanomechanical Behavior of β-SiC Nanowire in Tension: Molecular Dynamics SimulationsMATERIALS TRANSACTIONS, 2004
- Interfacial toughness measurements for thin films on substratesActa Materialia, 2002