Diamond-TiC composite with an ultrahigh Hugoniot elastic limit

The Hugoniot elastic limit (HEL) is widely adopted as an important criterion for assessing the dynamic strength of materials, representing the transition stress from elastic to plastic response prior to failure under shock compression. Nano-polycrystalline diamond currently holds the highest HEL of 208 (+/- 14) GPa. Here, we report a diamond-TiC composite (similar to 11.5 wt. % TiC) showing an ultrahigh HEL of at least 195 (+/- 3.5) GPa, which is comparable to that of nano-polycrystalline diamond. All measured velocity profiles on the diamond-TiC free surface exhibited a single-wave structure at shock pressures of 48-195 GPa. Moreover, the measured U-s-U-p (shock wave velocity-particle velocity) relation can be linearly fitted, indicating no elastic-plastic transition or solid-solid phase transition up to a shock pressure of 195 GPa. The diamond-TiC composite's compression ratio was similar to that of TiC but significantly higher than that of diamond. These extraordinary dynamic responses are intrinsically attributed to the unique microstructure in which diamond polycrystals are encased in a TiC matrix, providing protection against yielding. Our findings not only developed a mechanically reliable, lightweight, and high-performance armor material at low synthesis costs, but also provided new insights into the shock compression behavior of diamond composites.