Interfacial microstructure and mechanical properties of laminated composites of TiB2-based ceramic and 42CrMo alloy steel

Based on fusion and interdisffusion of the liquid ceramic and the molten steel, the laminated composite of TiB2-basedceramic and 42CrMoalloy steel consisting of 3-layer structure with the ceramic matrix, the intermediate and the steel substrate, was rapidly prepared by self-propagating synthesis with centrifugal-casting process, and within the intermediate the continuously-graded microstructures of span-scale-structured (micro-structured → micro-nanostructured → nano-structured) ceramic/alloy network developed while a conherent/particle-conherent relationship was kept in the interface of micro-nano/nanocrystalline TiB2 and Fe-Ni alloy base. Combining mechanical properties test with FESEM and HRTEM examination, it is considered that the in-situ achievement of the span-scale-structured continuously-graded intermediate of ceramic/alloy network microstructure not only presents the gradient joint with high flexural strength and high fracture toughness, but also presents the laminated composite with strong plastic deformation behavior and high ductility-like capacity during 3-point bending test. Meanwhile, the cooperative action of crack interlocking by fine Ni-based metallic films surrounding TiB2 platelets in the regions nearby the ceramic with precipitation strengthening by micro-nano/nanocrystalline TiB2 platelets in the intermediate was considered to contribute to the high interlaminar shear strength of 425±50 MPa.