Superior static and dynamic mechanical properties and high energy absorption in TiBw-TiCp reinforced TC4/Ti composites enabled by heterostructure design

This study addresses the challenge of enhancing the strength-plasticity synergy and energy absorption capacity of lightweight, ballistic-resistant materials. Guided by the principle of heterostructure design, a novel TiBw-TiCp/(TC4+Ti) composite was successfully synthesized. In this composite, pure Ti acts as the soft phase, TC4 as the hard phase, and B₄C particles as the initial reinforcement. The composite forms a unique multi-scale hetero-phasic interface, achieving a synergistic improvement in both strength and plasticity. The in-situ reaction between B₄C and the matrix generates TiB whiskers (TiBw) and TiC particles (TiCp), which significantly enhance the interfacial bonding between the soft and hard phases. The composite exhibits excellent comprehensive mechanical properties. It has a quasi-static ultimate tensile strength of 985 ± 10 MPa with a fracture elongation of 17.1 ± 0.5%. Under dynamic compression at a strain rate of 3000 s⁻¹, the true stress reaches 1562 MPa with a true strain of 27.8%, resulting in an energy absorption capacity of 408 MJ/m³. Analysis indicates that twinning accommodates plastic deformation in the soft phase, while multiple fractures of the whiskers effectively dissipate energy, thereby suppressing the formation of primary adiabatic shear bands (ASBs). The synergistic effect between the heterostructure and the reinforcements realizes an optimal strength-plasticity balance and enhanced energy absorption. This study provides a new design strategy and theoretical basis for improving the quasi-static and dynamic mechanical properties of titanium matrix composites.