Abstract: Metal matrix composites (MMCs) have attracted much attention for their properties such as lightweight, high specific strength, and reprocessing ability. Due to the complex interfacial interactions and microstructural evolution of MMCs, there are great difficulties in interpreting the structure-property relationship using experiments or continuum mechanical simulations. Therefore, we investigated the load transfer behavior and plasticity deformation mechanism of carbon nanotube/CoCrFeNi MMCs under high shock velocity by molecular dynamics simulations. The results showed that the introduction of carbon nanotubes (CNTs) significantly reduced the compressibility and increased the Hugoniot pressure. Typically, the maximum compressibility decreases by 7.9%, and the corresponding Hugoniot pressure increases by 47.7% when the CNT content is up to 1%. In particular, CNT has a higher and faster load transfer capacity, which causes carbon atoms in CNT to preferentially generate local displacements, inducing dislocation nucleation as well as stacking fault (SF) propagation. A high CNT content leads to severe strain localization, which induces effective shock wave energy consumption and phase transition. There are two different amorphous transformation mechanisms in the CNT/CoCrFeNi system: local crystal-glass transition owing to multi-CNT triggered complex SF networks, and homogeneous amorphization owing to the CNT collapse under higher shock velocity.

Key words: Metal matrix composites, Shock response, Molecular dynamics, Amorphous transformation