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

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