Techniques for in situ HVEM mechanical deformation of nanostructured materials

Abstract

We have developed two in situ HVEM experimental techniques which allow us to begin fundamental investigations into the mechanisms of deformation and fracture in nanostructured materials. First, a procedure for the observation of tensile deformation and failure of multilayer (ML) materials in cross-section is detailed. Second, the development of an in situ HVEM nanoindentor of surfaces and films on surfaces in cross-section is presented.Nanostructred ML materials often exhibit enhanced physical properties such as increased hardness and strength. There have been few (if any) direct observations of the mechanisms by which nano-scale structures affect deformation thereby enhancing mechanical performance. Nanoindenting has become a primary technique for measuring the mechanical properties of small volume materials. The mechanical properties of small volumes can vary greatly from bulk values. The elastic and plastic response and microstructure evolution in these small volumes under the indentor tip has never been dynamically observed before. Observation of the behavior of material under these conditions would no doubt further our understanding of the mechanical behavior of nanostructured materials.