Interfacial Oxide in Diffusion-Bonded Joints of Al-Binary Alloys by Transmission Electron Microscopy

摘要

The effects of alloying elements on the morphology and composition of interfacial oxides in diffusion-bonded joints have been investigated by TEM observations for Al binary alloys containing 0.06-2.0at% Mg, 1.0at% Si, 0.5at% Mn, 1.0at%Zn, and 1.0at% Cu. At the joint interfaces of the Al binary alloys, except for those of the Al-Mg system, continuous amorphous oxide films were observed at all bonding temperatures employed in this investigation. At the joint interfaces of the Al-Mg alloys, as described in a previous paper, the oxide altered gradually from amorphous films to crystalline particles 10-100 nm in size as the bonding temperature was increased. The difference in the behavior of interfacial oxide between the Al-Mg alloys and those of the other alloys can be explained thermodynamically by assuming that crystalline oxides were formed through reductive reactions of the oxide film of Al by Mg. EDS analyses of the amorphous oxide film at joint interfaces of the alloys revealed that Mg atoms were concentrated in the amorphous oxide film of the Al-Mg alloys prior to the formation of the crystalline oxide particles, whereas no concentration of other alloying elements could be detected in the amorphous oxide film of the other alloys.