Hierarchical crystalline–amorphous nanocomposites with high strength and large deformability enabled by elemental diffusion

Amorphous/nanocrystalline dual-phase structures have recently emerged as an effective way for overcoming the strength–ductility trade-off and breaking the limitation of the reverse Hall–Petch effect. Here, we proposed a new strategy to develop a hierarchical and interconnected amorphous–crystalline nanocomposite arising from the nanoscale elemental interdiffusion and oxygen adsorption behavior during thermal treatment processes. The nanocomposite consisted of a three-dimensional (3D) hierarchical network structure where the crystalline phase (Cr–Co–Ni–Al) was embedded into the Al–O-based amorphous phase network with critical feature sizes encompassing three orders of magnitude (from micrometer to nanometer scale). It can achieve ultrahigh compression yield strength of ∼3.6 GPa with large homogeneous deformation of over 50% strain. The massive interstitial atoms induced lattice distortion and hierarchical amorphous phase boundary contributed to the strength improvement. in situ Uniaxial compression inside a transmission electron microscope (TEM) revealed that the exceptional deformability of the nanocomposites resulted from the homogenous plastic flow of nano-sized amorphous phase and the plastic co-deformation behavior restricted by the nano-architected dual-phase interface. The proposed dual-phase synthesis approach can outperform conventional nanolaminates design strategies in terms of the mechanical properties achievable while providing a pathway to easily tune the microstructure of these nanolaminates. © 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.