Distinct Young's modulus of nanostructured materials in comparison with nanocrystals

Young's modulus (Y) of nanostructured materials (NSs) free of porosity is modeled with regard to the coordination number imperfection at grain boundaries. In light of it, Y of NSs is suppressed substantially in the whole solid temperature range, differing from the case of nanocrystals (NCs) where Y is enhanced at lower temperature (T) but weakened at higher T. It is found that, similar to NCs, the thermally-driven decline associated with the melting point depression plays an increasing role in suppressing Y of NSs on raising T. On the other hand, the lattice expansion and the bond weakening lead to a further suppression in Y of NSs independent of T, while the lattice contraction and the reinforced bonding strength result in an enhancement in Y of NCs, which should be responsible for the distinction in Y between NSs and NCs. The established functions were supported by available experimental and computer simulation results.