Journal of Materials Engineering and Performance, 2026 (SCI-Expanded, Scopus)
Functionally graded AA2024-B4C composites were fabricated by high-energy ball milling followed by hot pressing to evaluate the influence of B4C content (0-30 wt.%) and layer architecture (1-4 layers) on microstructural evolution and mechanical-ballistic performance. XRD and EDS analyses confirmed the formation of θ (Al2Cu) intermetallic phases and a well-controlled compositional gradient of B4C across the multilayered structures. The mechanical properties were strongly dependent on both reinforcement ratio and layer configuration. Among the investigated systems, the three-layer composite with 5/10/20 wt.% B4C exhibited the most balanced performance, achieving a hardness of 229 HBN (103% increase), a tensile strength of 360.7 MPa (70% improvement), and enhanced impact resistance with a peak load of 90.8 kN. Ballistic tests using 5.56 mm NATO ammunition revealed reduced entry (91 mm2) and exit (154 mm2) crater areas compared to monolithic counterparts. Although functionally graded metal-ceramic composites have been previously reported, the present study demonstrates a systematically designed AA2024-B4C gradient architecture in which reinforcement distribution is optimized to achieve a simultaneous improvement in hardness, strength, ductility retention, and ballistic energy absorption. The results highlight the effectiveness of tailored layer sequencing, particularly around 10 wt.% intermediate reinforcement, for advanced lightweight armor applications.