Investigation on the heat transfer characteristics of Haynes 230/ODS-Cu joints brazed by Ag-Cu filler

In this study, Haynes 230 and aluminum oxide dispersion strengthened copper alloy (ODS-Cu) have formed joints with strong interfacial joining, enabling efficient heat transfer across the joints. Effects of brazing temperature and holding time on the thermal conductivity and shear strength of Haynes 230/ODS-Cu joints are systematically investigated. The evolution of the joint microstructure is also studied. During brazing, the Ag-Cu braze melts and infiltrates the ODS-Cu. Simultaneously, the ODS-Cu in contact with the molten braze dissolves, releasing Al₂O₃ particles. An oxide-reinforced joint structure is formed in-situ. Ultimately, a brazing seam is formed at the joint, consisting of a Cu solid solutions (s,s) matrix with dispersed Al₂O₃ and Ag (s,s) particles. The brazing seam width reaches up to 821 μm. The thermal conductivity of the joints is explored over a testing temperature range from room temperature to 700 °C. Results indicate that the joint brazed at 850 °C for 10 min achieves optimal thermal conductivity, reaching a joint thermal conductivity of 23.3 W·m⁻¹·K⁻¹ at room temperature, and 50.5 W · m⁻¹ · K⁻¹ at 700 °C. And the shear strength of the joint is stable at 116 ± 12 MPa at room temperature. This study provides an important reference for obtaining brazed joints with high thermal conductivity.