Multiscale structure-mechanical property relationship and data-driven design of ultra-high temperature ceramics: A review

Ultra-high temperature ceramics (UHTCs) exhibit exceptional melting points, superior oxidation resistance, and outstanding ablation performance, positioning them as indispensable materials for extreme-environment applications. However, their inherent brittleness, high density, limited elasticity, and poor fatigue resistance restrict broader implementation. This review presents a rigorous, multiscale examination of interrelationships between UHTC structural characteristics and mechanical behaviors, addressing critical knowledge gaps in failure mechanisms and state-of-the-art design of strengthening and toughening strategies. The analysis commences with crystal-chemical principles and progresses through salient microstructural and mesostructural characteristics, followed by an exploration of thermally induced deformation and structural evolution at elevated temperatures. The dominated factors in mechanical degradation and corresponding strengthening and toughening mechanisms across nanoscale, microscale, and mesoscale levels are systematically dissected. Furthermore, we highlight recent advances in high-throughput screening within materials genome engineering and the integration of machine learning (ML) for rapid property prediction and structural optimization of UHTCs. Finally, prospective multiscale design strategies are proposed to synergistically optimize the balance of strength and toughness in UHTCs.