In recent years, heterogeneous nanostructured materials have been the focus of intense investigation due to their radically enhanced properties. These properties include improved radiation damage resistance, thermal stability, and ultrahigh hardness and strength. These outstanding properties are intimately tied to the influence and participation of the biphase interfaces on microscopic deformation mechanisms and microstructural evolution during mechanical straining. Important challenges include developing revolutionary ways to design and synthesize materials with novel biphase interfaces for stability and sustainability in thermomechanical extreme conditions. To meet these challenges, we have a research program to engineer the chemistry, structure, morphology of biphase interfaces in three-dimensions within heterogeneous nanostructured materials. We espouse a holistic approach and employ nanomaterial synthesis, atomic-scale modeling, dislocation theory, phase field dislocation dynamics, and micromechanics combined with experiment testing and characterization.