Brazing SiC ceramic to Al0.3CoCrFeNi high-entropy alloy using Ag-Cu filler metal

Realizing the joining of SiC ceramic to Al0.3CoCrFeNi high-entropy alloy is a technical interest for aviation, aerospace, and nuclear energy industry. In this study, the reliable brazing of SiC and Al0.3CoCrFeNi 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 Al0.3CoCrFeNi 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 Al0.3CoCrFeNi were crucial for the joint formation. (Ni, Fe, Co)(2)Si + graphite + Cr23C6/(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 Al0.3CoCrFeNi. 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 similar to 32.2 MPa was obtained at 850 degrees C for 10 min.