Influence of Immediate Deformation and Natural Ageing on Al 6XXX Series Alloy Nanostructural Evolution

Constellium extrusion are leading the way for automotive light-weighting by the development of high strength 6XXX series aluminium alloys. Alloys with yield stresses up to 400MPa are currently obtainable, but in order to further reduce the weight of the crash management system, these materials need improved levels of energy absorption on impact.

A novel fabrication route is under development to produce alloys with enhanced crushability, however, there is a lack of fundamental understanding of how the desired microstructure develops. There are a number of open questions surrounding the initial clustering mechanisms. The unique capability of the microscopy technique, atom probe tomography, with its ability to visualize and quantify the size and chemistry at the initial stages of clustering at the atomic scale, is essential to understanding the impact of each processing stage on the final microstructure, and Oxford University is the only facility in the UK with expertise in this area.

The aims of this project are to identify the effects of trace alloy additions on the cluster formation, and explore the impact of various processing parameters (time temperature, deformation) on the clustering kinetics. By working in close collaboration with Innoval Technology (Banbury ,UK), Constellium and the rapid prototyping centre at Brunel University, the subsequent impact on mechanical properties can be assessed, and a carefully controlled microstructure will then be engineered with improved crush properties. The project will develop atom probe tomography techniques to make direct atomic-scale microstructural comparisons across a range of processing treatment and alloy compositions. It will also incorporate site-specific Plasma Focused Ion Beam specimen preparation techniques and complementary microscopy, such as TEM, for a holistic characterisation of the effectiveness of the processed alloys. Ultimately the goal is to correlate this unique 3D nanoscale information to optimising the mechanical properties/performance for applications of these Al alloys in the automotive sector.
The project directly addresses the EPSRC theme, Manufacturing the Future. It also directly contributes to EPSRC priority areas such as: Lightweight Systems, Materials Characterisation and Structural Integrity and Materials Behaviour. It also has the potential to develop greater collaborative links in this area with other UK academic and industrial partners.

Themes: Engineering; Manufacturing the future; Physical sciences