Potential for Using Scandium in Extrusion Alloys

Paul Rometsch¹ and Jerome Fourmann²

¹Rio Tinto Aluminium, Saguenay, Québec, Canada
²Rio Tinto Aluminium, Chicago, Illinois, USA

Used with permission from the Proceedings of the Thirteenth International Aluminum Extrusion Technology Seminar (ET ’24), published by the Extrusion Technology for Aluminum Profiles Foundation and Aluminum Extruders Council.

Abstract. Scandium (Sc) can offer many benefits to aluminium alloys, such as significant strengthening, grain structure control and corrosion inhibition. However, Sc has rarely been used in extrusions due to cost and supply issues. Another but somewhat related challenge is that there are metallurgical aspects to be understood and exploited if maximum benefits are to be achieved from minimal Sc additions. This work explores the effects of small Sc additions (~0.1wt%) on selected extrusion alloys from among the 1xxx-, 3xxx-, 5xxx- and 6xxx-series alloys. The addition of Sc to 6xxx-series extrusion alloys is particularly challenging due to the potential loss of Sc to coarse non-hardening AlSiSc particles and due to the mismatch in aging temperatures between the Al3Sc and MgSi hardening precipitates. This work reveals possible pathways for processing different types of extrusion alloys to achieve maximum microstructure and property benefits per unit Sc addition.