Effects of interlayer on the interfacial microstructures and thermomechanical kinetics of explosive welded 2A14 aluminum alloy-niobium composite

Abstract

The explosive welding of 2A14 aluminum alloy and niobium with and without a 1060 Al interlayer is investigated by experiments and a two-step numerical simulation. Microstructure observations revealed a continuous molten layer with plenty of micro-defects at the joint interface by direct welding, and for the welding situation with an interlayer, straight and curled joints devoid of imperfections were obtained at the upper and lower interfaces, respectively. The tensile-shear strength for the direct welded samples was 84.4 MPa, while a rise of 38.2% was achieved for the composite with an interlayer. The coupled Lagrange-Eulerian simulation showed a dramatic decline in impact velocity and an obvious increase in collision area and duration due to the insertion of the interlayer, the resulting less kinetic energy loss at the joint interfaces eliminates the formation of the intermetallic compounds. In addition, the smoothed particles hydrodynamics simulation demonstrated that the distribution of strain, temperature, and pressure is more pronounced at the lower interface, and different bonding processes were elucidated for these two interfaces. The introduction of the interlayer strengthened the weldment by adjusting the way the interface accommodates the impact-induced strain.