Homogeneous, laminated, and functionally graded TiCp/TC4 composites: Microstructure, mechanical properties, and dynamic impact behavior

Homogeneous titanium alloys and titanium matrix composites (TMCs) suffer from poor impact resistance due to their uniform microstructure, limiting their application in high-strain-rate environments. In this study, three homogeneous materials—Ti-6Al–4V (TC4), 6 wt% (3–5 μm) TiC p /TC4 (6% TiC p /TC4), and 15 wt% (15–45 μm) TiC p /TC4 (15% TiC p /TC4)—and two heterogeneous materials—a titanium laminated composite (TLC, alternating TC4 and 6% TiC p /TC4) and a titanium functionally graded material (TFGM, gradient layering of the three compositions along the thickness direction)—were fabricated by hot-pressing sintering. Their microstructure, static mechanical properties, and dynamic impact behavior were systematically investigated. Results show that varying TiC p size and content leads to distinct microstructures and properties in homogeneous TMCs: 15% TiC p /TC4 exhibits the highest hardness (HV 566) and tensile strength (592 MPa) but reduced ductility; 6% TiC p /TC4 shows intermediate strength and best ductility; TC4 has the lowest strength. In TLC and TFGM, no distinct macroscale interfaces are observed; instead, fine-grained transition layers form, with TFGM exhibiting a more gradual microstructural variation. Under dynamic impact, all three homogeneous materials fracture. TLC shows improved early-stage deformation resistance and mid-stage energy absorption, with only localized surface fragmentation. Remarkably, TFGM rapidly reaches the highest stress and sustains strong energy absorption throughout the entire process, becoming the only material that remains completely intact without macroscopic fracture. This outstanding performance is attributed to the gradient transition layers, which avoid impedance mismatch and efficiently dissipate impact kinetic energy. This study provides a new design strategy for high-performance TMCs suitable for high-strain-rate impact environments.