DIFFUSION BONDING OF AL 6061 ALLOYS USING AN EUTECTIC REACTION OF AL-AG-CU

초록

Background It is well known that aluminum alloy A6061 are difficult to join because the solidus temperature of the alloys is low, i.e., it is close to the liquidus temperature of commonly used Al-Si fillers. Therefore, recently to overcome this problem, many workers have studied new filler metals, such as Al-Ge-Si-Mg, Al-Ge-Cu-Si-Mg, Al-Si-Cu-Mg and Al-Cu-Ni-Si with a low melting point. Compared to the conventional brazing which uses fillers of pre-determined compositions, the diffusion brazing forms liquid via eutectic reaction between the base metals and the filler inserted, thus lowers the joining temperature. This method has been used for joining aluminum alloys such as Al-B, Al-Li, and Al-Si. In this study, for the first time, a diffusion bonding of high strength aluminum alloy A6061 was performed using an eutectic reactions between Al (base metal’s element) and Ag, Cu (filler metal’s elements) at low temperature, and the dependency of joining conditions and heat treatments on the structural and mechanical properties of the brazed joints was examined. Results and Conclusions In this research, the melting point of insert metal tends to be decreased during diffusion bonding. That is, as each element, which is Ag, Cu in the insert metal and Al, Si, Mg in the base metal, diffused each other side then, it is considered that melting points decrease due to eutectic reaction between base metal and filler metal elements. Tensile strength of the joints, which was brazed at 560℃ for 30min then performed T6 heat treatment, was more than 290Mpa. This value is about 90% of tensile strength of the base metal.