Fabrication of textured (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2 high-entropy ceramics

Textured high-entropy boride ceramics, prototypically (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, with nearly single phase were fabricated for the first time by spark plasma sintering (SPS) of the corresponding powder, which was derived from boron/carbothermal reduction. Lotgering orientation factor calculation and the pole figures revealed that the c-axis of high-entropy boride grains aligned parallel to the SPS pressing direction after sintering and grains grew along the a,b-axis to form platelet-like morphology. The remarkably high Vickers’ hardness of ∼29 GPa was observed on both of the side surface and the top surface of textured ceramics. The surface perpendicular to the SPS pressing direction demonstrated an improved fracture toughness owing to the oriented elongated grains.