C Liu, C Shen, J Shen, B K Tsai, Y Zhang, Y Chen, Y Zhang, K Xu, D Paul, J Lu, H Li, Z Hu, X Sheng, A Wazeer, S Zhou, R E García, X Zhang, H Wang “In situ Studies on Microstructural Evolution and Thermally Activated Plasticity of (Co, Cu, Mg, Ni, Zn) O High-Entropy Oxide.” Acta Materialia, 122212, 2026. https://doi.org/10.1016/j.actamat.2026.122212

Abstract

High-entropy oxides (HEOs) offer promising structural performance due to their compositional complexity and stable single-phase structures. This study investigates the mechanical behavior of spark plasma sintered (Co, Cu, Mg, Ni, Zn) O using in situmicropillar compression from room temperature to 600 °C inside a scanning electron microscope, complemented by transmission electron microscopy and crystallographic orientation mapping. At room temperature, brittle transgranular fracture occurs with limited dislocation activity. At 400 °C, shear localization, Cu-rich secondary phases and delayed cracking emerge. At 600 °C, prominent plastic deformation is observed accompanied with work hardening. Microscopy studies reveal dislocation glide, slip band formation, grain fragmentation, and Cu-rich secondary phases. This study confirms temperature-dependent plasticity in (Co, Cu, Mg, Ni, Zn) O and demonstrates the potential of entropy-stabilized design in overcoming ceramic brittleness via microstructural engineering.