Multilayered composites based on light metals are promising materials in many applications. In the present work the 15-layered clad, composed of alternately stacked of Ti(Gr.1) and AA1050-H24 alloy sheets of 1 mm thick has been investigated with respect to determination of the kinetic of the Al3Ti phase growth. The defect-free multilayered composite was successfully formed by explosive welding technology. Then EXW samples were modified via annealing at the temperature of 600oC in closed die under pressure of 44 MPa for various times ranged between 1 and 10 h. Transmission and Scanning Electron Microscopy examinations were conducted in order to study the kinetic of the elements migration across the interfaces between the layers of the Al/Ti composite. The macro-scale observations of samples after EXW revealed that wavy interfaces were always formed in layers near the explosive charge. The increase of the distance from the top surface leads to flattening of the interface with very thin reaction layer between Al and Ti sheets. During annealing the kinetic of the Al3Ti phase growth is similar near all interfaces and coincides with data from other works. It was found that despite the loading after 10 h of annealing still only small part of Al-sheets undergoes dissolution and the width of the reaction layer does not exceed 5-8 µm.
In this work, the effect of heat transfer during explosive welding (EXW) and post-processing annealing on the microstructural and chemical composition changes have been thoroughly analysed using scanning and transmission electron microscopies and X-ray synchrotron radiation. Several combination of explosively welded metal compositions were studied: Ti with Al, Cu with Al, Ta or stainless steel, stainless steel with Zr or Ta and Ti with carbon steel. It was found that the melted metals exhibit a strong tendency to form brittle crystalline, nano-grained or even amorphous phases during the solidification. For all analysed metal combinations most of the phases formed in the zones of solidified melt do not appear in the equilibrium phase diagrams. Concurrently, the interfacial layers undergo severe plastic deformation forming nano-grained structures. It has been established that these heavily deformed areas can undergo dynamic recovery and recrystallization already during clad processing. This leads to the formation of new stress-free grains near the interface. In the case of low temperature and short time post processing annealing only the melted zones and severely deformed layers undergo recovery and recrystallization. However, drastic changes in the microstructure occurs at higher temperature and for longer annealing times. Applying such conditions leads to diffusion dominant processes across the interface. As a consequence continuous layers of intermetallic phases of equilibrium composition are obtained.