Crystalline-Amorphous Nanocomposites Strengthened and Toughened with Hierarchical and Interconnected Nanostructure

Amorphous-nanocrystalline dual phase structure were proved to be an effective way for overcoming the strength-ductility trade-off and break the limitation of reverse Hall-Petch effect. Here, we proposed a new strategy to develop a hierarchical and interconnected amorphous-crystalline dual-phase nanocomposite by the nanoscale elements interdiffusion and partition. The nanocomposite consists of three-dimensional continuous crystalline phase (Cr-Co-Ni-Al) embedded in amorphous network (Al-Ni-Co or Al-O). This unique microstructure can achieve ultrahigh yield strength of ~3.6 GPa with a large homogeneous deformation over 60% strain, effectively suppressing the plasticity instability occurred in conventional nanocrystalline alloy. In situ Transmission Electron Microscopy studies reveal that exceptional strength-ductility combination results from the pronounced dislocation nucleation-movement-annihilation activities promoted by 3D nano-architected dual-phase interface, the homogenous plasticity flow of nano-sized amorphous phase, and deformation-induced devitrification induced self-toughening effect. This strategy breaks through the composites design limitations of conventional nanolaminates and provides a paradigm to develop high-strength and high-ductility dual phase nanocomposites with hierarchical microstructure.