Explosively welded multilayer Ni–Al composites

Abstract

In this study, the structure of explosively welded Ni–Al multilayer composites was investigated. In particular, the interface between Ni and Al plates was studied using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). Continuous interlayers of mixed Al and Ni were found at the interface. The Al and Ni in these zones were heated above their melting temperatures, non-uniformly mixed, and rapidly solidified. Several intermetallic phases, including the decagonal phase and metastable Al9Ni2, were observed in these zones using electron diffraction. A cellular dislocation structure formed in the Ni plates and a polygonized dislocation structure formed in the Al plates due to the extremely high strain rate deformation and heating. Subsequent heat treatment at 620°C led to the rapid formation of stable intermetallic layers at the interfaces. The growth of the intermetallic layers was considerably faster in the explosively welded composite than in the reference sample.