Microstructure and mechanical behaviors of Gasar porous Cu/G4335V steel joint brazed by Ag-28Cu-0.75Ni alloy

Abstract

Cu/steel composites have the advantages of low cost and high heat dissipation performance, which make them ideal materials for applications in the industrial heat dissipation field. Because of the unique pore structure, the Gasar porous Cu is more excellent in heat transfer performance. However, systematic research still needs to be done on the joining technologies of Gasar porous Cu/steel. In this paper, Gasar porous Cu was joined to G4335V steel using Ag-28Cu-0.75Ni. The microstructure, shear strength, and fracture behavior of the Gasar porous Cu/G4335V steel joint were investigated. The results show that a clear interface of the brazed joint and no brazing defects were found. The joint microstructure mainly comprises α-Cu (ss.), β-Ag (ss.), and Ag-Cu eutectic phase. As the pore diameter of Gasar porous Cu increased, the joining area of the Gasar porous Cu/G4335V steel joint became larger, thereby improving the shear strength of the joint. For the same pore diameter, the shear strength of the mode 1 joint (The load direction and the pore direction are parallel to each other. The pore direction refers to the growth direction of the pore.) was higher than that of the mode 2 joint (The pore direction and the load direction are perpendicular to each other). The fracture analysis indicated that the joint crack was initiated in α-Cu (ss.) and propagated along the banded α-Cu (ss.). The joint fracture was a mixed fracture mechanism that combined ductile-brittle fractures.