Achieving (TiZrTaNbCr)C/Zr alloy brazed joints with outstanding high-temperature oxidation resistance and mechanical property

High entropy carbide ceramics showed outstanding high-temperature oxidation resistance and high-temperature mechanical property, showing a great application potential in nuclear reactor cladding materials. This work proposed a brazing technology to realize the connection of (TiZrTaNbCr)C/Zr-4 brazed joint by Ni-based filler, which exhibited an outstanding high-temperature oxidation resistance and mechanical property. The interface microstructure and phase compositions of the (TiZrTaNbCr)C/Zr-4 joint were investigated. The brazing seam was primarily composed of Zr(s,s), Zr₂Ni and ZrCr₂. The ZrC and Cr₂₃C₆ interface reaction layer and the diffusion of Ni elements ensured the interface bonding. Different to previous researches, the second phase of Cr₂₃C₆ was observed in the ZrC reaction layer, improving the strength of interface reaction layer. As a result, a highest shear strength of 105 MPa was achieved at the (TiZrTaNbCr)C/Zr-4 brazed joint. Furthermore, the high temperature shear strength at 800 °C of (TiZrTaNbCr)C/Zr-4 joint was 91 MPa, maintaining 87 % of the room-temperature shear strength. Compared to Zr-4 alloy, the (TiZrTaNbCr)C and BNi-2 filler showed an outstanding oxidation resistance, and the shear strength of the joint was maintained 67 % after oxidized at 900 °C for 8 h.