Effects of Bismuth on the Microstructure and Mechanical Properties of AISi9Cu3(Fe) Die Casting Alloys

摘要

In secondary die cast Al alloys, Bismuth is generally considered an impurity element and present as a trace element in commercial foundry alloys. In the present work, the influence of different Bi content on the microstructure and mechanical properties of a commercial die cast AlSi9Cu3(Fe) alloy is investigated. The Bi level ranges between 0.015 and 0.3 wt.%. The results show that the presence of Bi seems to not produce significant changes in the microstructure and mechanical properties. Fine Bi-rich compounds are observed in the die cast alloys and they are malnly distributed in the interdendritic regions and along graln boundaries. TEM investigations revealed a complex Bi-Bi_2Mg_3 eutectic structure, which presents malnly rod-type and blocky morphology.