Models for the behavior of boron carbide in extreme dynamic environments

Abstract

We describe models for the behavior of hot-pressed boron carbide that is subjected to extreme dynamic environments such as ballistic impact. We first identify the deformation and failure mechanisms that are observed in boron carbide under such conditions, and then review physics-based models for each of these mechanisms and the integration of these models into a single physics-based continuum model for the material. Atomistic modeling relates the composition and stoichiometry to the amorphization threshold, while mesoscale modeling relates the processing-induced defect distribution to the fracture threshold. The models demonstrate that the relative importance of amorphization and fracture are strongly dependent on the geometry and impact conditions, with the volume fraction of amorphized material being unlikely to be significant until very high velocities (~3 km/s) are reached for geometries such as ball impact on plates. These connections to the physics thus provide guidelines for the design of improved boron carbide materials for impact applications.