Microstructural evolution and ageing behaviour of the low Cu:Mg ratio Al–Cu–Mg alloys containing scandium and lithium

The microstructural evolution and ageing behaviour of Al–4.0Mg–1.5Cu–1.0Li–(0.2Sc)–0.12Zr alloys were investigated. The results indicate that small addition of Sc can enhance the ageing strengthening effect while the time taken to the ageing peak is prolonged. And the Sc-containing Al–4.0Mg–1.5Cu–1.0Li–0.2Sc–0.12Zr alloy exhibits a promising combination of strength and ductility. TEM observations show that the precipitation processes during ageing can be modified by the small addition of Sc. [Copyright &y& Elsevier]