Effect of minor cerium additions on microstructure and mechanical properties of cast Al – Cu – Mg – Ag alloy

Abstract

A series of cast Al – Cu – Mg – Ag based alloys with minor cerium additions have been investigated using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. It was found that increasing the cerium content from 0 to 0.45 wt-% increased the tensile strength at the test temperatures of 25°C and 300°C. The high strength of the casting alloys with cerium is attributed to the refined grains and the high density of fine ω precipitates. However, the addition of 0.2 wt-%Ce to the alloy with 0.25 wt-%Ti induced a detrimental effect on the mechanical properties. The cause of this was found to be the formation of the intermetallic compound Al_x Ti₆ Ce₃ Cu.