YSZ has been widely used as a TBC material, but its phase change at high temperatures limits its development, thus the need for developing new thermal barrier materials resistant to high temperatures. Rare-earth aluminate ceramics with a garnet structure (Yb₃Al₅O₁₂) have been considered as a potential thermal barrier material. The melting point of Yb₃Al₅O₁₂ is 2000 °C, which has a potential high temperature application prospect. However, Yb₃Al₅O₁₂ has lower thermal expansion and higher thermal conductivity than YSZ, which is a widely employed thermal barrier coating (TBC) material. To overcome these obstacles, (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂, a high-entropy ceramic, was prepared by a solid-state reaction and pressureless sintering. The thermal conductivity of the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ was 3.48 W/(m·K) at 300 K, approximately 25.48% lower than that of the Yb3Al5O12 (4.67 W/(m·K)). The thermal expansion coefficient of the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ was 9.28 × 10⁻⁶ K⁻¹ at 673-1273 K, approximately 18.52% higher than that of the Yb₃Al₅O₁₂ (7.83 × 10⁻⁶ K⁻¹, 673-1273 K). When the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ was annealed at 1550 °C for 7 days, its average grain size only increased from 0.7 μm to 1.3 μm. Moreover, the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ exhibited better chemical stability and a lower grain growth rate than the Yb₃Al₅O₁₂. This study reveals that (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ is a promising candidate for the future generation of thermal barrier materials.

The isothermal compression tests of the nickel-based superalloy Waspaloy were carried out under various temperatures from 1040 to 1120 °C and strain rates from 0.01 to 10 s⁻¹ with the height reduction of 60% and the flow stress curves were obtained. The curves show that the flow stress is greatly affected by the temperature and strain rates. Regression analysis of the experimental results was carried out to learn about the deformation behavior through the Arrhenius equation and came to the conclusion that the activation energy of Waspaloy is 669.7 kJ/mol. The constitutive equation of the Waspaloy was constructed. Meanwhile, the processing maps of the Waspaloy for the power dissipation and the flow instability were constructed. The processing map of the power dissipation and the flow instability depicts that the strain plays a major role in the processing maps. The instability zone is prone to appear at higher strain rates with the increasing strains. According to the instability processing map, there are three unsafe regimes around 1040–1120 °C/1.5–10 s⁻¹, 1040–1080 °C/0.02–0.1 s⁻¹ and 1110–1120 °C/0.02–0.3 s⁻¹ that should be avoided during deformation process. The power dissipation maps show that the maximum dissipation is prone to appear at low strain rates (0.01 s⁻¹) when the strain is about 0.1~0.6 while at middle strain rates (0.1–1 s⁻¹) when the strain is over 0.6, and when the true strain is 0.9, the optimum processing condition is around 1060–1120 °C/0.1–1 s⁻¹. The dynamic microstructures under different temperatures and strain rates were also obtained. We concluded that lower strain rates and higher temperatures are more applicable to obtain fully-recrystallized microstructures. Based on the instability maps and the power dissipation maps and the dynamic microstructures, the optimum deformation conditions are determined to be around 1080–1100 °C/0.1–1 s⁻¹ and 1040–1120 °C/0.01 s⁻¹.

The joining of solid-state sintered silicon carbide (SiC) was achieved using a novel Si-Ti-Al ternary alloy via vacuum brazing. This study investigates a predominantly non-carbide-dominated interfacial bonding mechanism and the influence of brazing temperature on joint microstructure, mechanical properties, and high temperature reliability. The high Si content promoted the incorporation of Ti into Ti–Si phases within the brazed seam, thereby limiting the amount of Ti available for reaction with SiC. No continuous TiC layer was detected within the spatial resolution of the employed characterization methods. Minor discrete Al₄C₃ precipitates were identified at the interface but did not constitute the dominant bonding phase. Brazing at 1360 °C yielded an optimal microstructure featuring highly regular coral-like eutectic clusters, resulting in a peak room temperature shear strength of 102.8 MPa. The joints also exhibited favorable high temperature reliability, maintaining a shear strength of 58.4 MPa at 1000 °C. Microstructural analysis following thermal exposure revealed partial coarsening of primary blocky phases and interfacial Al₄C₃ precipitates via Ostwald ripening, which contributed to the reduction in high temperature strength. Nevertheless, the robust retention of fine eutectic clusters ensured satisfactory structural stability under thermal loading. This work provides a viable strategy for designing Si-based brazing fillers for high-performance SiC ceramic joining.