@article{QIN2021, author = {Mingde QIN and Qizhang YAN and Yi LIU and Jian LUO}, title = {A new class of high-entropy M3B4 borides}, year = {2021}, journal = {Journal of Advanced Ceramics}, volume = {10}, number = {1}, pages = {166-172}, keywords = {high-entropy ceramics, high-entropy borides, reactive sintering, spark plasma sintering, Ta3B4-prototyped orthorhombic structure}, url = {https://www.sciopen.com/article/10.1007/s40145-020-0438-x}, doi = {10.1007/s40145-020-0438-x}, abstract = {A new class of high-entropy M3B4 borides of the Ta3B4-prototyped orthorhombic structure has been synthesized in the bulk form for the first time. Specimens with compositions of (V0.2Cr0.2Nb0.2Mo0.2Ta0.2)3B4 and (V0.2Cr0.2Nb0.2Ta0.2W0.2)3B4 were fabricated via reactive spark plasma sintering of high-energy-ball-milled elemental boron and metal precursors. The sintered specimens were ~98.7% in relative densities with virtually no oxide contamination, albeit the presence of minor (4-5 vol%) secondary high-entropy M5B6 phases. Despite that Mo3B4 or W3B4 are not stable phase, 20% of Mo3B4 and W3B4 can be stabilized into the high-entropy M3B4 borides. Vickers hardness was measured to be 18.6 and 19.8 GPa at a standard load of 9.8 N. This work has further expanded the family of different structures of high-entropy ceramics reported to date.} }