Investigation of mechanical properties of boroncarbide under dynamic loading by molecular dynamicsmethods

Boron Carbide (B4C) is investigated by molecular dynamics simulations to examine its mechanical behavior on the dynamics loading. Atomistic shock compression simulations are carried out in [0001] and [1010] impact directions for that purpose. Interaction between atoms is defined with reactive force field (reaxFF). Hugoniot curves are obtained and Hugoniot elastic limits (HEL) are determined for both directions. HEL points occur at about 17 and 19 GPa in [0001] and [1010] directions, respectively. Resistance of material to structural deformations is higher for [1010] direction compared to [0001]. Three wave fronts develop in shock wave profile in the material. The shock velocity Us - particle velocity Up relations in plastic region has bilinear nature. Amorphous state is observed above impact speeds 2.0 and 3.0 km/s, in [0001] and [1010] impact directions, respectively. Buckling of C-B-C chains and lattice rotation as a whole which are considered as the causes of deformation occur before amorphisation, the degree of both of which depends on impact direction and impact speed. The changes in the structural order of B4C is investigated using radial distribution function (RDF) analysis. Our numerical results compare favorably with available experimental results. Keywords: Boron Carbide, Shock Compression, Molecular Dynamics, ReaxFF II