On the Applicability of Explosively Bonded Materials of Aluminum-Other Metal to Transition Piece for Joinning Dissimilar Metals (Report 1)

A study has been made of the properties of explosively bonded interface between aluminum and dissimilar metals such as copper and mild-steel.Tests were carried out on the effect of heat-cycle on the structures and mechanical properties of bonds in order to clarify the applicability to the transition pieces.In the explosive bonding of Al-Cu, alloying layers were considerably formed in the interface, and their constitution was θ (CuAl2) phase mainly. By heat-cycle, the growth of another alloying layers which seemed to be γ2(Cu9Al4) phase was observed between Cu-matrix and θ(CuAl2) phase.Alloying layers observed in explosively bonded Al-Fe seemed to be composed of the eutectic of α(Al) and θ(FeAl3) phase. By heat-cycle, θ(FeAl3) phase grew to exist by itself for the most part. However, there was some possibility of existing of another intermetallic compounds such as η(Fe2Al5).The shear strength of the explosive bonds in Al-Cu and Al-Fe lowered with raise of temperatures of heat-cycles and there was observed a change in their fracture mode. This resulted from the influence of the formation or growth of intermetallic compounds by heat-cycle.But by heat-cycle of 3 pass welds the growth of an alloying layer was not so often observed as that by 550°C×3 min. From this result, there can be confirmed the applicability of these bonded materials to transition piece. However, it was necessary to pay full attention to selection of explosive conditions, since the cracks and voids which seemed to reduce the properties of explosive bonds were observed in the alloying layer of bonds.