Phase evolution and thermal stability of novel high-entropy (Mo0.2Nb0.2Ta0.2V0.2W0. 2)Si2 ceramics

Authors：Ye, Songbo; Zhu, Jinpeng^*; Wang, Hailong^*; Li, Mingliang; Huang, Zhihao; He, Jilin

Source：Journal of the European Ceramic Society, 2022, 42(13): 5314-5322.

DOI：10.1016/j.jeurceramsoc.2022.06.067

• High-entropy disilicides
• First-principles calculations
• Phase evolution
• Thermal stability

Owing to the high melting points and high-temperature stability, transition-metal disilicides are potential components for aerospace, automotive, and industrial engineering applications. However, unwanted oxidation known as PEST oxidation severely limits their application owing to the formation of volatile transition metal oxides, especially in the temperature range of 500-1000 degrees C. To overcome this problem, a new class of high-entropy disilicides, (Mo0.2Nb0.2Ta0.2V0.2W0.2)Si-2, was selected by first-principles calculations and then successfully fabricated using a hot-pressing sintering technique. Furthermore, the phase evolution, thermal expansion behavior, thermal conductivity, and oxidation behavior were systematically investigated. Compared with MoSi2, (Mo0.2Nb0.2Ta0.2V0.2W0.2)Si-2 possessed a lower thermal conductivity (10.9-14.7 W.m(-1).K-1) at 25-1000 degrees C, higher thermal expansion coefficients (8.6 +/- 1.3(-6) K-1) at 50-1200 degrees C, and especially an excellent thermal stability at 500-1000 degrees C owing to slow diffusion and selective oxidation. This work provides a strong foundation for the synthesis and application of high-entropy disilicides.

• Institution
  郑州大学