Eutectic bonding of Al 6061 alloy using Cu insert metal

초록

Al 6061 alloy has been brazed with conventional filler metal like Al-12Si alloy. However, if brazing temperature is not closely controlled, erosion and bad wettability is appeared due to little difference in melting temperature between the base metal and filler metal. In this study, The eutectic bonding characteristics of Al 6061 alloy using pure Cu foil(8㎛ in thickness) has been investigated at lower temperature. The eutectic temperature of Al-Cu alloy is 548℃. Differential temperature analysis was carried out with Al 6061/Cu/Al 6061 clad to investigate the starting temperature of eutectic reaction between Al 6061 alloy and pure Cu. The alloy melt, which has the eutectic composition, started to form at 510℃. It seems to be ternary or quaternary eutectic reactions by Al-Cu-Mg-Si system. Therefore, the bonding can be accomplished above 510℃. The investigation on the effect of temperature was done at the temperature range between 510℃ and 575℃. The results showed that the bonding strength increased as the bonding temperature increased. The base materials of bonded part ,which was bonded at 575℃, was fractured at 172㎫. Therefore, the bonding strength could be estimated over it. The bonding structure showed isothermal solidification structure at longer bonding time because it has enough time for copper to diffuse into aluminum matrix. As a result of interfacial analysis of microstructure using TEM, oxide layer through the interface was observed as amorphous structures.