Study on mechanical properties and microstructure of bonding interface of Ta-2.5W/TC11 explosive-welded composite pipes

To test the feasibility of the Ta-2.5W/TC11 explosion welding process, a composite pipe with a Ta-2.5W tantalum alloy cladding and a TC11 titanium alloy base was fabricated using explosion welding. The microstructure, elemental distribution, and mechanical properties of the interface between the Ta-2.5W/TC11 explosion-welded composite pipe were systematically analyzed using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and a universal testing machine. The results showed that the interface of the composite pipe consisted of both a flat interface and a wavy interface, with a large number of molten layers. Within the molten layers, some defects such as voids and inclusions were observed. Elemental diffusion occurred on both sides of the composite pipe interface, driven by concentration gradients, and the diffusion area in the molten layer is larger than the directly bonded interface. Furthermore, mechanical property tests indicated that the axial compressive yield strength of the prepared Ta-2.5W/TC11 composite pipe reached as high as 1 040 MPa. However, in the radial flattening test, the radial compression rate was only 10.5%, and the interface shear strength was only 76 MPa. These results indicate that the Ta-2.5W/TC11 composite pipe has high strength in the axial direction, and the explosion welding process for fabricating Ta-2.5W/TC11 composite pipes is feasible, though the bonding performance of the interface still needs improvement.