This work deals with the experimental investigation of the mechanical properties of nanowires. Experiments are conducted in a dedicated system inside the electron microscope. The mechanical response of various material systems is probed, the underlying deformation mechanisms are elucidated and subsequently put into context with mechanical size effects.

This book investigates the fatigue mechanisms and crack initiation of Ni, Al and Cu on a small-scale in the Very High Cycle Fatigue regime by means of innovative fatigue experimentation. A novel custom-built resonant fatigue setup showed that the sample resonant frequency changes with increasing cycle number due to fatigue damage. Mechanisms such as slip band formation have been observed. Cyclic hardening, vacancy and oxidation formation may be considered as early fatigue mechanisms.

In this work, different nanocrystalline metals and alloys were investigated by a synchrotron-based in situ XRD mechanical testing technique in order to investigate the dominant deformation mechanisms. All tested samples show a succession and coexistence of several mechanisms, regardless of grain size, loading condition, or sample geometry. However, the relative shares of the individual mechanisms strongly vary and depend on parameters such as grain size, sample purity, and alloy composition.

The 1/2111 screw dislocations in bcc iron are studied by atomistic simulations. An analytical yield criterion captures correctly the non-Schmid plastic behavior. A model Peierls potential develops a link between the atomistic modeling at 0 K and the thermally activated dislocation motion. All predicted features agree well with experimental observations. This work establishes a consistent bottom-up model that provides an insight into the microscopic origins of the plastic behavior of bcc iron.

Nanostructured metals with maximal grain or twin sizes of less than 100 nm have advanced properties like increased strength.As beneficial as these microstructures can be for the strength of materials, they are not infinitely stable. During mechanical loading these metals tend to coarsen and lose their beneficial structure. Besides electron microscopic analysis of fatigued samples, in situ cycling tests were conducted in order to observe structural degradation during mechanical loading.