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 at 1500 degrees 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.