Understanding the co-precipitation mechanisms of Al3(Sc, Zr) with strengthening phases in Al–Cu–Li model alloys

© The Minerals, Metals & Materials Society 2018. The addition of scandium (Sc) is known to be beneficial to the properties of aluminium alloys. Sc has a significant impact on the strength, especially when combined with zirconium (Zr) where nano-size Al3(Sc, Zr) dispersoids are formed. However, to date the extraction of Sc from its oxide has been too expensive to promote its use on the industrial scale. New extraction methods have made the process more cost-effective. So far, there has been only limited research done concerning the effect of Sc in Al–Cu–Li alloys. Interaction between the Al3(Sc, Zr) dispersoids and other precipitate phases containing copper (Cu) and/or lithium (Li) have been rarely studied. In this study, the impact of Sc and Zr on precipitation and further the properties of Al–Cu–Li alloys is investigated. Mechanical properties were examined by quasi-static tensile tests. Using TEM, the morphology and size of dispersoids and precipitates were examined.