Solid‐State Reactions of SiC/W–25Re Alloy and Thermal Stability of SiC/Ti/W–25Re Alloy under High‐Temperature Annealing

Solid‐state reactions of SiC/W–25Re alloy and SiC/Ti/W–25Re alloy are investigated under the high‐temperature annealing at1 500 °C. The interface reaction layer between SiC and W–25Re alloy is composed of WC– WSi₂– W₅Si₃– W–Re sigma phase – dendrite microstructure. Solid‐state reactions between W and SiC form two types of W‐silicides and the relative depletion of W brings formation of the W–Re sigma phase. In order to prevent direct interfacial reactions, Ti layer is intercalated as a secondary buffer layer. Compared to the original interface, thicknesses of both reaction layer and dendrite layer are significantly decreased. Although the thermal reaction of Ti and W brings inhomogeneous characteristics, the proposed functionally graded structure is expected to enhance the thermal stability.