Precipitation behavior of strip cast Al–Mg–0.4Sc–0.15Zr alloy under single and multiple-stage aging processes

Abstract

In this study the precipitation behavior of an Al–Mg–0.4Sc–0.15Zr alloy produced by strip casting (FLEXCAST) technology at Novelis is investigated. As-cast, as well as different cold rolled specimens, were heat treated in a single-stage aging process, and a double-stage aging process was examined. Conventional mechanical properties and microstructural measurements were performed on both the as-cast and processed materials. In addition, TEM studies were performed at different stages of heat treatment. The mechanical properties results show that peak aging at 300°C is dependent on the prior amount of cold rolling, hence the dominant effect is recovery especially at the short period of aging. The results also indicate that even at the relatively long time of aging, i.e. 200h, the structure is not dominated by the formation of precipitates. Observations indicate that only at a relatively high aging temperature, i.e. 450°C, substantial amounts of non-coherent precipitates are present in the microstructure.