Deformation behavior and amorphization in icosahedral boron-rich ceramics

Abstract Among hard materials, icosahedra-based boron-rich ceramics are only second to diamond-based structures. This class of ceramics possesses lower density, higher thermal and chemical resistance, and can be easily mass-produced compared to diamond-based materials. The present article reviews contemporary knowledge of atomic structures, mechanical properties and deformation mechanisms of a range of boron-rich ceramics, including different allotropes of boron, polymorphs of boron carbide, and futuristic materials such as boron suboxide, “BAM” materials and their derivatives. Despite their high-hardness and strength, many icosahedral boron-rich ceramics are prone to a unique deleterious deformation mechanism under high pressure, called “amorphization”, which causes loss of strength and catastrophic failure. This article presents a critique of established approaches that explain the amorphization phenomena. Main highlights include the demystification of Raman spectrum of amorphized boron carbide using a multi-scale atomistic computational approach and atomistic investigation into connection between high-pressure deformation, such as those in shock conditions and rise in temperature up to melting. We finally probe avenues for enhancing performance of these ceramics well beyond contemporary thresholds, by proposing research pathways using rigorous computational material informatics.