Interfacial bonding mechanism and mechanical properties of Cu-Ni-Si/1010 steel bimetallic laminated composites prepared by continuous solid/liquid bonding

Abstract

The Cu-Ni-Si/1010 steel bimetallic laminated composites (BLCs) were prepared by continuous solid/liquid bonding, and the microstructure, mechanical properties and interfacial bonding mechanism were investigated. The results show that the microstucture of Cu-Ni-Si mainly consists of α-Cu, and a small quantity of Ni-Si rich phases which distribute at the grain boundaries. Meanwhile, the microstucture of 1010 steel is composed of ferrite (F), pearlite (P), and a small amount of bainite (B). A flat and well-bonded interface is formed between two layers due to the diffusion of elements. The diffusion layer is identified as the Fe based solid solution containing Ni and Si by TEM. The interfacial bonding mechanism is revealed using Fick's second law and thermodynamic methods. The results show that the diffusion coefficients of Ni and Si in Fe are higher than those of in Cu, and the molar Gibbs free energies of mixing (GmixM) of Fe-Ni and Fe-Si are lower than those of Cu-Ni and Cu-Si, indicating that Ni and Si tend to diffuse to Fe. The ultimate tensile strength, yield strength and elongation of Cu-Ni-Si/1010 steel BLC are 378 MPa, 233 MPa and 25.4 %, respectively, which lie between those of individual Cu-Ni-Si and 1010 steel. The tensile shear results show that the interface is always well bonded, and no cracks are found at the interface during the deformation. The fracture of the Cu-Ni-Si/1010 steel BLC occurs at the Cu-Ni-Si side, suggesting that the bonding strength is larger than that of the Cu-Ni-Si.