Fabrication and impact performance of nickel-based ceramic/novel high-strength and high-toughness steel graded composites

To enhance the multi-impact resistance of armor, this study innovatively employed ultra-gravity field combustion synthesis to prepare nickel-based ceramic (TiC–TiB 2 ) and novel high-strength and high-toughness steel gradient composites (Functionally Graded Materials, FGM). By regulating Ni content (20 %-50 %wt.%), the interfacial transition layer was optimized. Microstructural characterization demonstrated that the 50 % Ni sample formed a continuous gradient layer approximately 100 μm thick, with ceramic phases uniformly distributed in the metal matrix. This composition achieved optimal comprehensive performance: compressive strength reached 465 MPa with a compression ratio of 5.2 %. Plate impact spallation experiments using a single-stage light gas gun revealed that the gradient material exhibited a spall strength of 2.915 GPa. Crack analysis showed that the gradient material developed only non-penetrating microcracks without significant ceramic layer spalling, whereas the reference bonded structure exhibited complete ceramic fragmentation. The fracture mechanism displayed gradient evolution characteristics: the high-strength and high-toughness steel layer underwent microvoid coalescence-induced ductile fracture, while the ceramic layer manifested a combination of brittle intergranular fracture and ductile fracture in the metal matrix. Finite element simulation were adopted to analyze the impact resistance of the FGM as well. Research has demonstrated that the functionally graded design effectively suppresses interfacial failure through continuous material transitions, significantly enhancing resistance to repeated impacts. This provides a theoretical foundation for designing novel impact-resistant protective materials.