Residual Stresses in Metallic Multilayers

The study of residual stresses in metallic superlattices is of great importance. Properties of these materials are a consequence of their extreme strain states. With respect to single films, both the determination methods and the magnitude of the stresses may differ in multilayers. X-ray strain determination must be used with caution because of possible interference effects. The large amount of disorder tends to suppress the modulation on asymmetrical peaks. Stress deduced from wafer bending experiments may contain a non negligible interfacial contribution. The very large stresses (≥1Gpa) determined in the superlattices imply very high yield stresses, possibly related to size effects. Anomalous strain free lattice parameters are frequently reported. They may be related to the occurrence of segregation during the growth.