Atomistic-to-Macroscopic Mechanical Modeling of (HfNbTaZr)B₂ High-Entropy Ceramics via a Developed Interatomic...

Atomistic investigations of high-entropy diborides (HEBs) are currently hindered by the lack of reliable interatomic potentials. Here, we develop an analytical bond-order potential (ABOP) for the Hf/Nb/Zr/Ta/B system, parameterized via an intelligent global optimization algorithm and trained against extensive ab initio data. The developed potential accurately captures the structural, elastic, and mechanical properties of various materials, including metals, intermetallics, alloys and diborides. Additionally, the chemical short-range order (CSRO) in dynamic simulations under finite temperatures is correctly predicted. Molecular dynamics (MD) simulations reveal that HEB nanopillars exhibit brittle failure driven by shear banding, while CSRO shows limited influence on the mechanical response. Simulated nanoindentation gives modulus (435 GPa) and hardness (27.7 GPa) consistent with theoretical predictions and experiments. Furthermore, we establish a multiscale framework by extracting an atomic traction-separation law and rescaling it based on fracture energy conservation (G_c = 21.01 J/m²) for finite element cohesive zone simulations. This approach captures the brittle intergranular failure of polycrystalline HEBs, effectively bridging atomic-level mechanisms with macroscopic property predictions.