Lead P.I. - Dr. Jason R. Trelewicz

The deliberate combination of individual materials into engineered composite structures provides a unique opportunity to address the intrinsic limitations of monolithic structural materials.  An example of this is in metallic glass matrix (MGM) composites, where the limited ductility of monolithic amorphous alloys deriving from plastic flow localizing into shear bands can be combated by incorporating crystalline heterogeneities.  In parallel, interfacial engineering such as in metallic nanoglasses (MNG) holds promise for enhancing mechanical properties via strain delocalization.  In these different classes of materials, the underlying mechanisms seemingly operate at entirely disparate length scales – tens of micrometers in MGM composites and only tens of nanometers in MNGs. Our research in this area is on exploring the mechanisms underpinning strain delocalization by combining molecular dynamics simulations of shear localization with characterization and nanomechanical testing to elucidate the role of glassy interfaces and the presence of a distributed crystalline phase on strain delocalization.  The figure above illustrates a summary from (a) onset of shear banding and property mapping nanoindentation experiments on MGM composites and (b) atomistic simulations of shear localization in nanoglasses.  A broader study of interface engineering in metal matrix composites is being pursued in systems containing metal-ceramic interfaces formed in situ during processing with a focus on novel strengthening mechanisms in light-weight structural alloys.