Effects of Excess Si, Excess Mg and Fe on Precipitation in 6061 Aluminum Alloys during Recycling Process

摘要

Aluminum alloys 6061 contained excess Si, Mg and Fe were examined from a view point of recycling. Number density of inclusions was increased with adding excess amounts of these elements into 6061 alloys. Peak hardness in the alloy contained excess Si was increased, while those in the alloys contained Mg, Fe and both Mg and Si were decreased in comparison with a 6061 base alloy. Quantitative analyses of inclusions by means of SEM-EDX system showed that most parts of inclusions were composed of Al, Fe and Si, while in the alloy contained excess Mg, inclusions with high Si concentration were observed. Precipitates which contribute to age hardening were believed to be beta" on the basis of TEM observations. Definition of effective amounts of Si content for age hardening was proposed.