Effect of Ni interlayer on strength and microstructure of diffusion-bonded Mo/Cu joints

Mo and Cu were bonded successfully by means of diffusion bonding using a Ni interlayer. The tensile strength of the joint increases firstly and then decreases with the bonding temperature or holding time increases. Compared with 79 MPa which was the maximum value of Mo/Cu joint, the maximum tensile strength of joint with Ni interlayer was 97 MPa. The interfacial structure of the joints was studied by SEM, EPMA, EDS and XRD, the results showed that the different atoms diffused to each other in the bonding process and no intermetallic compound appeared. MoNi and NiCu solid solutions formed in the joint. The fracture of the joint had taken place in the Mo/Ni interface rather than in the Ni/Cu interface and the fracture way of the joints was brittle fracture.

► Mo and Cu were bonded successfully by diffusion bonding using Ni interlayer. ► The Mo/Ni/Cu joint can be obtained excellent performance than the Mo/Cu joint. ► The tensile strength increases firstly and then decreases. ► There were solid solution layers across the Mo-Ni and Ni-Cu interface. ► The fracture way of the joint was brittle fracture on the Mo-Ni interface.