Experimental and numerical analysis of the formation behavior of intermediate layers at explosive welded Al/Fe joint interfaces

The microstructural characteristics and formation mechanism of intermediate layers at the explosive welded Al/Fe wavy interface were investigated by experimental and numerical analyses. Two types of intermediate layers were obtained at the wavy joint interface produced at an impact velocity of 750 m/s and an impact angle of 15°. The layer that was formed in the tail-side included the area showing a dendritic structure consisting of Al3Fe and Al5Fe2. This indicated that local melting occurred in the area. In contrast, the layer that was formed in the front-side showed no evidence of melting. The formation behavior and temperature change at the Al/Fe interface formed by an oblique collision were simulated by the smoothed particle hydrodynamics (SPH) method. The simulation results revealed that on the tail-side, a mixture of Al and Fe particles formed and a large local temperature increase exceeding the melting temperature of Fe and Al occurred. The front-side showed a small temperature increase. The composition ratio of Al and Fe, and the temperature distribution at the joint interface calculated by the SPH simulation provided plausible explanations for the formation of two types of intermediate layers in each position.