Thermal conductivity optimization in SiC/Ti6Al4V joints with Cu foam interlayer

The growing demand for advanced thermal management solutions in the aerospace industry has led to integrating SiC ceramics and Ti6Al4V titanium alloy into high-performance components. In this study, SiC/Ti6Al4V joints were fabricated using AgCuTi braze combined with the Cu foam interlayer. The microstructure and properties of the joints were studied systematically. Ti₃SiC₂ and TiC phases were formed along the SiC interface, while various Ti[sbnd]Cu reaction layers with different Ti/Cu ratios were observed on the Ti6Al4V side. The brazing seam was primarily composed of silver solid solution (Ag(s,s)) and copper solid solution (Cu(s,s)). The Cu foam interlayer plays a crucial role in regulating interfacial reactions and reducing residual stresses. It partially consumes the active element Ti, preventing excessive reactions with the SiC ceramic, thereby improving the interfacial joining along the SiC interface. Due to partial melting of the Cu foam, the foam framework still can be retained after brazing, which effectively mitigates residual stresses. Effects of varying brazing temperature/time and Cu foam thickness were evaluated. The highest thermal conductivity of 23.6 W·m⁻¹·K⁻¹ at room temperature and 32.2 W·m⁻¹·K⁻¹ at 500 °C was achieved at 840 °C for 10 min with a 130 μm Cu foam interlayer. Also, a highest shear strength of 42.0 MPa was achieved. This study demonstrates the potential of brazing techniques to provide innovative solutions for advanced thermal management in demanding applications.