We prepared the novel high‐entropy (xRE1/x)2Si2O7 (RE = Y, Yb, Er, Sc, Gd and Eu, x = 2–6) ceramics by a two‐step method for the application of thermal environmental barrier coatings (TEBCs), and the effect of configuration entropy and lattice distortion on microstructures and thermal properties at high temperature were investigated. The results showed that the configuration entropy resulted from mass disorder can only contribute to the stability of thermal properties and microstructure. Lattice distortion should be responsible for reduction in thermal properties, which may be due to the enhancement of atomic nonharmonic vibration, resulting in intensified phonon scattering and hindering atomic amplitude oscillation. As‐prepared high‐entropy (Y1/6Yb1/6Er1/6Sc1/6Gd1/6Eu1/6)2Si2O7 ceramic exhibited the relatively low thermal diffusivity, thermal conductivity and coefficient of thermal expansion, which were 0.89–0.50 mm2 s–1, 1.99–2.50 W m–1 K–1 and (3.01–3.78) × 10–6 K–1 in the temperature range of 293–1373 K, respectively. This work provides a solid guarantee for the application of TEBC materials.
To improve the ability of rare‐earth (RE) silicates to resist molten calcium–magnesium–aluminosilicate (CMAS) at high temperature, a novel high‐entropy (4RE0.25)2Si2O7/(4RE0.25)2SiO5 (RE = Y, Yb, Er, and Sc) multiphase ceramic was prepared by a two‐step process. During sintering, (4RE0.25)2SiO5 can react with SiO2 at the grain boundaries of (4RE0.25)2Si2O7, which can not only purify the grain boundary but also promote the growth of the original (4RE0.25)2Si2O7 grains, thereby significantly improving the ability to resist molten CMAS corrosion at high temperature. After corroding at 1500°C for 48 h, the reaction layer of the multiphase ceramic was only 55 μm thick. Our results confirm that the high‐entropy RE silicate multiphase ceramics represent an effective way to improve the ability to resist molten CMAS corrosion at high temperature.
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