The Benefits of Trace Cu in Wrought Al-Mg Alloys

TL;DR

This study evaluates the effects of trace copper on the mechanical properties of Al-Mg alloys, demonstrating that low Cu content alloys are robust and suitable for recycling and paint-baking applications.

Contribution

It introduces a refined phenomenological model to distinguish recovery and precipitation effects, clarifying Cu's limited impact on alloy response.

Findings

Mechanical response is not strongly affected by low Cu levels.

The model effectively separates recovery and precipitation contributions.

Alloys show robustness to composition variations, beneficial for recycling.

Abstract

The softening and strengthening contributions in pre-deformed and aged Al-Mg-Cu alloys containing 3wt.%Mg and 0.5wt.%Cu are evaluated by a combination of microscopy, mechanical testing and modelling. A refined phenomenological model for the work hardening response, accounting for the separate effects of recovery and precipitation, is shown to be suitable for an unambiguous determination of the precipitation hardening contribution in these alloys. Significantly, it is found that the mechanical response of these alloys is not strongly impacted by Cu content (in the low Cu content regime), pre-deformation level or aging temperature meaning that the alloys are robust with respect to variations in composition. This is interesting from the perspective of alloy design concepts based on `recycling friendly' compositions in applications that include paint-baking.