Rate‐Dependent Compressive Behavior and Failure Mechanisms of TiB ₂ –B ₄ C Composite Ceramics

ABSTRACT To investigate the strain‐rate‐dependent compressive behavior of TiB 2 –B 4 C composite ceramics, quasi‐static tests and dynamic compression experiments were conducted using a universal testing machine and a split Hopkinson pressure bar system. Scanning electron microscopy‐based fractography was employed to examine failure mechanisms, and a modified microcrack‐driven model was used to interpret the strain‐rate effect. The results show that the compressive strength increases from approximately 4.73 ± 0.16 GPa at 10 − 3 s − 1 to 6.12 ± 0.18 GPa at an average strain rate of 3093 s −1 , demonstrating a pronounced strain‐rate strengthening effect. Microstructural analysis reveals a transition in fracture mode: intergranular fracture along TiB 2 /B 4 C boundaries dominates at low strain rates, whereas transgranular fracture of TiB 2 grains is prevalent at higher strain rates. The modified model yields a strain‐rate exponent of ∼1, indicating a narrower and more abrupt intermediate strain‐rate regime compared with monolithic ceramics. These findings suggest that the activation of smaller defects and two‐phase microstructural interactions are key factors controlling dynamic strength. The study provides fundamental insight into the mechanisms governing strain‐rate sensitivity in TiB 2 –B 4 C composites and offers guidance for optimizing their microstructure for high‐rate and protective structural applications.