As Young’s modulus (YM) is a structure insensitive property, size of the sample should not matter. But it does. The YM for a gold chain is not the same as YM for a gold nano-wire. Why? Thanks to Prof.S.Ranganathan sir (IISc) for posting this question in TRAERF site. I had this doubt.
Reason for this behaviour is so called "fibrous paradox". Dont know the exact english term - in German its "Faserparadoxon". Bulk materials contain a certain amount of defects. Due to small volume of nano-wires, probability to have defects in the wire is low which results in changed YM.
Reason for this behaviour is so called "fibrous paradox". Dont know the exact english term - in German its "Faserparadoxon". Bulk materials contain a certain amount of defects. Due to small volume of nano-wires, probability to have defects in the wire is low which results in changed YM.
At nano scale, the assumption that material is continuum is not appropriate. So size wont matter as long as it is only in macro scale. Material properties at micro/nano scale cannot be directly correlated with that of macro scale properties because the material cannot be considered as a continuum anymore.
True. Currently, there is an interesting development on electrospinning of ceramic nanofibres. These ceramic nanofibres become very flexible, while bulk ceramics are very brittle.
See for instance: S. Huang, H. Wu, M. Zhou, C. Zhao, Z. Yu, Z. Ruan, W. Pan, A flexible and transparent ceramic nanobelt network for soft electronics, NPG Asia Mater., 6 (2014) e86.
Young modulus is sensitive to grain size at the nanoscale level. It decreases when the nano-grain size decreases until the amorphous state that is the state where YM is the lowest. See: C.A. Schuh, T.C. Hufnagel, and U. Ramamurty: Acta Mater.,
2007, vol. 55, pp. 4067–4109
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructures