Small-scale mechanical behavior of intermetallics and their composites

To model and predict the mechanical behavior of composite materials, knowledge of the properties of their constituent phases as well as how they interact with each other is required. Although these mechanical properties can sometimes be deduced from measurements on bulk specimens, it is not always possible due to difficulties in producing bulk materials with compositions and structures similar to those of the individual phases in the composite. In such cases, in situ measurements of mechanical properties are needed. We review here our recent work on the application of nanoindentation and neutron diffraction to investigate the in situ mechanical responses of Cr-Cr3Si and NiAl-Mo, two model eutectic composites that were chosen because they can be processed by directional solidification to yield well-aligned lamellar and fibrous microstructures. Phase-specific mechanical properties were measured and correlated with bulk behavior. We will discuss recently developed techniques that improve the accuracy of mechanical property measurements at small microstructural length scales.