Increase of specific interfacial coherence in nanocrystalline ceramic-metal composites

A new strategy to establish a large number of interfacial coherence in nanocrystalline multi-phase composites was proposed. The route consisting of amorphization, crystallization and in-situ reaction was demonstrated using WC-Co composites as a typical example. Characteristics of crystal nucleation, growth crystallography, and phase transformation were studied in detail on the atomic scale for the ceramic grains. Mechanisms for the formation of specific interfacial coherence in the prepared nanocrystalline ceramic-metal composites were disclosed. Assisted by the interfacial coherence, the continuity of local deformation is maintained from metal to ceramic phase, resulting in a uniform strain extension instead of stress concentration at the interfaces. The present nanocrystalline composite achieved outstanding mechanical properties with simultaneously high hardness and fracture toughness. The findings in this work provide new insights to tailor grain structure and interface relationship in cermet composites for superior comprehensive mechanical performance.