The effect of scandium and zirconium on the microstructure, mechanical properties and formability of a model Al–Cu alloy

The addition of zirconium (Zr) together with scandium (Sc) is known to increase the strength of Al alloys. This work explores the impact of Sc and Zr on the extrudability of a model extruded Al-4 wt%Cu alloy. A traditional material’s property which can be directly related to the energy required to form a certain alloy is an alloy’s flow stress. The flow stress behaviour is evaluated from the stress displacement curves recorded during extrusion. The addition of Sc and Zr is found to result in an increase of the flow stress of 14% when the yield strength in the T8 temper increases by 100%. This increase in flow stress is compared to other heat treatable Al alloys and it is found that Sc and Zr result only a minor increase in the flow stress.