Institutional and technical history of requirements-based strategic armor ceramics basic research leading up to the multiscale material by design materials in extreme dynamic environments (MEDE) program. Part II: Dynamic effects on the physics and mechanisms of advanced ceramics such as boron carbide

Abstract

This paper follows a historical background on requirements-based strategic armor research, leading to the materials in extreme dynamic environments program presented in Part I, now focusing on the developed technical aspects and state-of-the-art. It starts with some background on dynamic testing techniques and a structural ceramics review. Then, selected armor ceramics research results and relevant single-grain anisotropic crystal physics, microstructure, and defect mechanics mechanisms: Including pivotal armor ceramics research results prior to the adoption of the strategic research objective (SRO). Next, multiscale characteristics, crystal physics, planar features, anisotropy, and relevant mechanisms will be described. The historic progression/evolution of multiscale lightweight armor ceramics research results will be summarized, including multiscale dynamic deformation and damage characteristics. The focus of the following sections will be on the role of defects, quasi-plasticity, and anisotropic crystal physics properties, including preexisting single grain synthesis and process-induced planar features (aka twins) and planar deformation features (PDF); for example, nano-amorphization in boron carbide. A new model for boron carbide processing planar features will be discussed. A schematic diagram illustrating the hypothetical formation of PDFs in a dynamic event is also presented. An expended canonical equation is introduced, suggesting possible strategies for boron carbide research using the canonical figures of merit approach. Finally, we highlight the efficacy of the materials by design process and approach in a multiscale framework for the simultaneous experimental and theoretical research trajectories guided by the accepted canonical equation.