Joining C/C composite in a few seconds using refectory high entropy alloy fillers via spark plasma sintering

C/C composites were flash joined with ZrHfNbTa and TiZrHfTa refectory high entropy alloy fillers using spark plasma sintering within a short time frame of 16 s. The influence of different fillers on the joint morphology, shear strength at room temperature, and fracture behavior was investigated. The results indicated that the ZrHfNbTa filler completely transformed into carbide after flash SPS joining for 16 s, while the TiZrHfTa filler exhibited a (Ti-Zr-Hf-Ta)C phase, along with a small amount of TiTa rich alloy phase in the central area. The shear strengths of the obtained C/C composite joints using ZrHfNbTa and TiZrHfTa fillers at room temperature were close, with value of 16.0 ± 2.4 MPa and 14.1 ± 2.0 MPa, respectively. This work introduces a novel and flexible processing approach for joining high temperature resistant materials.