Abstract
Toward a sustainable society, there is a demand for multi-material structures that utilize aluminum, which has high electrical conductivity, is lightweight, and is easy to recycle. To realize the manufacturing of multi-material structures, the challenges are to develop a low-cost and versatile aluminum dissimilar material joining technology and a structure that facilitates a circular economy. We have clarified a short-time bonding technique of less than one second that uses a eutectic reaction induced by electric current in air to fracture the base material, and have systematized the bonding conditions. In this study, in order to clarify the bonding mechanism of the current-induced high-speed eutectic reaction, bonding experiments and observations were carried out, and the interface behavior and morphology were analyzed during the interface temperature rise process and the isothermal process after the eutectic temperature of 548°C was reached. As a result, in the isothermal process, while the metabolism of the generation and discharge of the eutectic melt was repeated, the thickness of the reaction layer at the interface was constant (thickness 2.0 to 2.9 μm), interface morphology was maintained, and the soundness of bonding behavior was confirmed. The time required for the metabolism to reach the bonding strength required for base material fracture was 0.1 s or more. It was confirmed that the ϒ1 phase was formed by solid-state diffusion at the aluminum/copper interface due to current induction, and it was found that the eutectic melt appeared from both the aluminum side and the copper side during the heating process. We have analyzed the behavior of the interface during current-induced high-speed eutectic bonding and clarified the importance of the metabolism accompanying the generation and discharge of the eutectic melt.
