A qualitative and quantitative investigation of nonmetallic inclusions in molten Al–Mg, Al–Cu, and Al–Zn–Mg–Cu alloys

Abstract

In this work, a qualitative and quantitative investigation on inclusions in molten Al–Mg, Al–Cu, and Al–Zn–Mg–Cu alloys, and the evolution behavior of inclusions in these three alloys during off-line and on-line purification steps were studied via the porous disc filtration technique. It was found that the removal of oxide from 2219 and 5A06 aluminum alloys melt via furnace refining is difficult, both of which can only remove the oxide by about 27 %, whereas the furnace refining can remove oxide from 7A04 aluminum alloy melt effectively, it can reduce the oxide by 55 %. Moreover, we determined that the furnace refining and degassing can reduce the boride content in 5A06 aluminum alloy effectively, but the boride content in 7A04 and 2219 aluminum alloy varied little after these two purification processes. Also, the furnace refining and on-line degassing were found to increase the carbide in 7A04 aluminum alloy, which was not found in the other two alloys. Further, we correlated the relationship between the slopes of the melt mass-time curves of the filtrates and the inclusion content for 2219, 5A06, and 7A04 aluminum alloys, which implies a higher concentration of inclusion possesses a lower slope for the melt mass-time curves of the filtrates. The obtained result could offer some guidelines for the production of high-quality ingot for the studied three alloys.