Abstract: The deformation incompatibility of components is a bottleneck restricting the exaltation of the strength and ductility of composites. Herein, the coherent transition interface was designed and produced in hexagonal boron nitride nanosheets (BNNSs)/Al composites by reaction sintering route, expecting to relieve the deformation incompatibility between BNNSs and Al. It is demonstrated that with the sintering temperature for composites raising from 600 °C to 650 °C, 700 °C and 750 °C, different interface bonding characteristics, which involve nucleation and growth of AlN continuous nanolayer, were confirmed. Furthermore, first-principles calculations show that the generation of the coherent transition interface improved the interfacial bonding strength of BNNSs/Al composites through covalent bonds. The composites with coherent transition interface exhibit excellent strength-toughness combination in tensile and impact tests. The finite element simulation and in-situ approach under tensile tests were applied to investigate the influence of transition interface structure on deformation behavior of BNNSs/Al composite. It is found that the generation of the transition interface can not only weaken the stress partitioning behavior in the elastic stage, but also constrain the crack initiation and propagation behavior in the elastic-plastic stage and plastic stage, thereby improving the deformation compatibility between BNNSs and Al. The present work provides a novel view into the breakthrough for the trade-off relationship of strength and ductility by coherent transition interface design in nanocomposites.

Key words: Nanocomposites, Al-BNNSs system, In-situ interface reaction, Coherent transition interface, Strength and ductility