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Realizing the joining of SiC ceramic to Al 0.3 CoCrFeNi high-entropy alloy is a technical interest for aviation, aerospace, and nuclear energy industry. In this study, the reliable brazing of SiC and Al 0.3 CoCrFeNi high-entropy alloy was realized by inactive AgCu filler, which lays the foundation for the following research on ceramic-high-entropy alloy dissimilar joining. The interfacial microstructure was characterized by a scanning electron microscope and transmission electron microscope in detail, and the influence of Al 0.3 CoCrFeNi dissolution on interfacial reactions was studied. The effect of brazing temperature on microstructure evolution and mechanical properties was discussed. The results indicated that elements Ni, Fe, Co, and Cr from Al 0.3 CoCrFeNi were crucial for the joint formation. (Ni, Fe, Co) 2 Si + graphite + Cr 23 C 6 /(Cr, Fe) 23 C 6 + (Ni, Fe, Co) 2 Si formed adjacent to SiC and (Fe, Co, Cr, Ni)-Si silicide + Cu(s,s) + Cu-Ni-Al-rich phase formed next to Al 0.3 CoCrFeNi. The reaction layers on SiC side thickened and the morphology of (Fe, Co, Cr, Ni)-Si-and Cu-Ni-Al-rich phase experienced distinct changes with the increasing temperature. The highest strength of ∼32.2 MPa was obtained at 850 • C for 10 min.

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The brazing of Titanium alloy to Aluminum alloy is of great significance for lightweight application, but the stable surface oxide film limits it. In our work, the surface oxide film was removed by the ion bombardment, the deposited Cu layer by magnetron sputtering was selected as an interlayer, and then the contact reactive brazing of TC4 alloy to Al7075 alloy was realized. The microstructure and joining properties of TC4/Al7075 joints obtained under different parameters were observed and tested, respectively. The results revealed that the intermetallic compounds in the brazing seam reduced with the increased brazing parameters, while the reaction layer adjacent to TC4 alloy continuously thickened. The shear strength improved first and then decreased with the changing of brazing parameters, and the maximum shear strength of ~201.45 ± 4.40 MPa was obtained at 600 °C for 30 min. The fracture path of TC4/Al7075 joints changed from brittle fracture to transgranular fracture, and the intergranular fracture occurred when the brazing temperature was higher than 600 °C and the holding time exceeded 30 min. Our work provides theoretical and technological analyses for brazing TC4/Al7075 and shows potential applications for large-area brazing of titanium/aluminum.