The connection between the microstructure of sputter-deposited Ag/Ni superlattices and their elastic response has been investigated in order to give evidence of the role of interface effects in determining the physical properties of this kind of structure. X-ray and transmission electron microscopy (TEM) experiments have shown that the Ag/Ni interfaces are semicoherent even at very low periods; in addition, there are an appreciable number of structural imperfections, such as stacking faults, twins and atomic disorder at the interfaces. The softening of the shear effective elastic constant c 44, observed at low periods by means of Brillouin scattering experiments, can be simulated by assuming the presence of a modified layer at each interface, 2/2 atomic planes thick, characterized by a reduced value of the shear effective elastic constant. A comparison between the set of experimental data relating to Ag/Ni superlattices and existing theoretical models suggests that elastic anomalies can be attributed to the presence of atomic disorder at the interfaces, rather than to coherency strains, surface tension stresses or electronic effects.

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