Microstructure and texture distribution in the bonding interface of Cu/Al composite tube fabricated by explosive welding

The Cu/Al composite tube has been shown to significantly increase heat exchange capacity and reduce production costs which are extensively used in condensers, evaporators, refrigeration equipment, and so on. In this work, a Cu/Al composite tube was successfully fabricated by explosive welding technique. The interface morphology and grain information in the radial-axial direction (RD-AD) and radial-tangential direction (RD-TD) sections were investigated by optical microscopy (OM), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD). The results showed that the Cu/Al composite tube had a well-welded bonding interface without obvious defects. A flat wavy structure composed of fine grains was generated at the bonding interface in the RD-TD section while a small wavy structure was formed in the RD-AD section. In addition, the phase transformation occurred in both bonding regions which produced mainly CuAl and Khatyrkite metallic phases. Furthermore, the distinct impact pressure and plastic deformation patterns in the two sections lead to different dynamic recrystallization structures and texture distributions.