Microstructure and mechanical properties of Ti3SiC2 and Al0.3CoCrFeNi brazed by the in-situ formed phases reinforced FeCoCrNiCu/Ti composite interlayer

This study presents a brazing technique for joining Ti₃SiC₂ ceramic and Al_0.3CoCrFeNi HEA (high entropy alloy) using a FeCoCrNiCu/Ti composite interlayer. The resulting brazing seam features a BCC+FCC dual-phase matrix with in-situ-formed TiC reinforcement phases. Thermodynamic simulation analysis confirms the phases present in the joint. WDS (wavelength dispersive spectroscopy) elemental distribution studies further validate the interface composition. Optimized brazing parameters, including Ti interlayer thickness, temperature, and holding time, promote solid solution formation and minimize excessive reactions. A 20 μm Ti interlayer ensures optimal joint formation, with brazing at 1180 °C yielding crack-free joints and medium Ti₃SiC₂ dissolution. The most homogeneous solid solution matrix is achieved with a 10-minute holding time. The moderate hardness of phases in the seam reflects their good plasticity, aiding stress release. Shear strength testing shows optimal values (∼85 MPa) at room temperature, with only a slight decrease (∼78 MPa) at 1000 °C. Additionally, the microstructure of the joints remains stable after 10 thermal cycles. This technique demonstrates the potential for producing durable, high-performance joints between Ti₃SiC₂ and Al_0.3CoCrFeNi HEA.