Investigating the initial cluster formation mechanisms in high-strength 6XXX aluminium alloys by atom probe tomography

Lead Research Organisation: University of Oxford
Department Name: Materials

Abstract

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, particularly when there is a high density of dislocations. 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 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 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 the University of Warwick and Brunel University and industrial partners such as Jaguar Land Rover.

Themes:
Engineering
Manufacturing the future
Physical sciences

Publications

10 25 50

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509711/1 01/10/2016 30/09/2021
1922133 Studentship EP/N509711/1 01/10/2017 31/03/2021 James Famelton
 
Description Open day presentation 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact 30-40 prospective University students and approximately half as many parents/guardians attended a presentation given by James Famelton about the background of precipitation strengthening in aluminium alloys and a flavour of the current research.
Year(s) Of Engagement Activity 2018
 
Description Presentation at the European Atom probe workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation about technical elements of the research conducted to date, in particular data analysis. This sparked my involvement in presenting at a further smaller workshop in more depth about my work.
Year(s) Of Engagement Activity 2018