The Effect of Interface Morphology on the Electro-Mechanical Properties of Ti/Cu Clad Composites Produced by Explosive Welding

The effect of interfacial microstructure on the electro-mechanical properties of explosively welded titanium and copper plates is discussed. Mechanical testing proved that using detonation velocities ranging from 2000 to 3000 m s(-1) and stand-off distances from 1.5 to 9.0 mm, joints that satisfy the strength criteria for a good quality clad were produced. Scanning electron microscopy images show that all interfaces exhibit a wave character. It was noticed that as the stand-off distances and detonation velocities increase, the amplitude and period of the waves, as well as the quantity of the melt zones, increase as well. Also, as the interface waviness and volume fraction of the melt zones increase, the resistivity increases substantially. The experimental data demonstrate that the bonding between both metals is always achieved by surface melting of several tenths of a nanometer, which can be detected only by transmission electron microscopy. Most of the phases that form within the melt zones do not appear in the equilibrium phase diagram and show an amorphous/nano-grained structure. Only a very small amount of equilibrium phases such as CuTi3, Cu3Ti, Cu4Ti3 was revealed employing synchrotron X-ray diffraction.