Interfacial microstructure and mechanical properties of TZM alloy/graphite heterogeneous joints vacuum brazed with Ti-23Co filler alloy

The heterogeneous structure bonded by TZM alloy and graphite serves as a critical material for divertor components in nuclear fusion reactors. In this work, a reliable bonding of TZM alloy and graphite was achieved using the self-developed Ti-23Co brazing alloy. The effects of brazing temperature and holding time on the interfacial microstructure and mechanical properties of the TZM/graphite brazed joints were systematically investigated, and the interfacial formation mechanism was analyzed in detail. The typical interfacial microstructure of the brazed joint can be described as TZM/Ti(s, s)/Ti₂Co/TiC/graphite. With increasing brazing temperature and prolonging holding time, the shear strength of the joint first increased and then decreased. Under the optimized brazing parameters of 1130 °C for 10 min, the joint exhibited a maximum shear strength of 19.03 MPa. This investigation provides a theoretical foundation and technical support for the high-performance joining of TZM alloy and graphite dissimilar materials in nuclear energy applications.