Microstructure evolution and shear strength optimization in SiC ceramic/MA956 ODS steel joints brazed with Cu–5Ti filler

Joining of SiC ceramic and ODS steel is of great significance for the next-generation candidate component of nuclear reactors. In this work, SiC ceramic and MA956 ODS steel were brazed successfully using Cu–5Ti filler alloy. The effects of brazing temperature on the microstructure evolution and mechanical properties of the joints were investigated, and the microstructure evolution mechanism was explored. The joints brazed at 1060 °C for 10 min exhibited a typical interfacial microstructure composed of SiC /Cu_6.69Si + graphite/TiC/Ti₅Si₃/Cu(s,s) /TiFeSi /Ti(Fe,Cr)Si/MA956. SiC exhibited pronounced thermal sensitivity and easily over-reacted with Cu, resulting in an excessively thick ceramic decomposition layer, which was widely observed on the joint fracture surface. The shear strength of the joints initially increased and then decreased with rising brazing temperature. At 1060 °C, the maximum shear strength of 42 MPa was obtained due to the moderate reaction between the base materials and the filler. This work will help provide more options for the selection of nuclear reactor structural materials.