Formation of intermetallics at the interface of explosively welded Ni-Al multilayered composites during annealing

Abstract

Abstract. The Ni-Al multilayer composite was fabricated using explosive welding. The zones of mixing of Ni and Al are observed at the composite interfaces after the welding. The composition of these zones is inhomogeneous. Continuous homogeneous intermetallic layers are formed at the interface after heat treatment at 620 °C during 5 h. These intermetallic layers consist of NiAl 3 and Ni 2 Al 3 phases. The presence of mixed zones significantly accelerates the growth rate of intermetallic phases at the initial stages of heating.

Microstructure of the interface zone after explosive welding and further annealing of A1050/Ni201 clads using various joining conditions

“…This observation is inconsistent with the presented work, where arrangement of the colliding plates always led to the wavy nature of the area of joining; however, these waves were significantly broader, when the aluminum alloy acted as a flyer plate. Nevertheless, the same microstructure components inside the waves such as fine dendrites or vortex were observed as in [18,19]. Chemical composition measurements confirmed that the melted zones were not homogeneous and consisted of a mixture of Al and Ni with various concentrations of these elements; however, the analytical resolution of EDS in SEM is insufficient for fine-grained regions as well as the swirled ones and for revealing the type of possible intermetallic phases existing in the melted regions.…”

“…In respect to previous works about EXW of Al/Ni system, the current paper demonstrates how the interface develops with respect to the various localizations of the colliding plates (aluminum alloy acts either as a flyer plate or base plate). The authors of previous reports [18,19] concluded that the influence of the arrangement of the colliding plates is not significant; however, the discrepancies regarding the localization of the plates could be noticed as can be seen in figure in the work [18]. A similar observation was made by Fronczek et al [1,20], where Ti Gr.2 and Al 1050 were explosively welded.…”

“…They confirmed that when the low explosive loads were used, the interface was flat, and on the other hand, with the application of higher explosive loads, the wavy interface was observed [7]. To our best knowledge, only a few papers have discussed the Al/Ni explosive welds in detail [17][18][19]. Gerland et al [17] indicated the possibility of joining of the thin Ni films with Al alloy by EXW technique.…”

“…In their paper, a brief description was given, regarding the explosion velocity influence on the interface microstructure (character of interface, amount of intermetallics or damages such as cracks) and roughness of the film surface. Two other works [18,19] dealt with Al/Ni multilayered composites manufactured with 4200 m s -1 . These studies focused on the microstructure of interfaces and their changes resulting from their annealing at 620°C.…”

“…These studies focused on the microstructure of interfaces and their changes resulting from their annealing at 620°C. In particular, Ogneva et al [18] indicated the existence of two types of interfaces: Ni/Al and Al/Ni, which, in regard to their mutual location, differed in shape and amount of the melted region thickness. The Ni/Al interfaces were flat, while Al/Ni were characterized by periodic variation of the mixing zones.…”