Three-dimensional characterization of fatigue-relevant intermetallic particles in high-strength aluminium alloys using synchrotron X-ray nanotomography

Abstract

Second-phase particles and small porosities are known to favour fatigue crack initiation in high-strength aluminium alloys 2050-T8 and 7050-T7451. Using high-resolution X-ray tomography (320 nm voxel size), with Paganin reconstruction algorithms, the probability that large clusters of particles contain porosities could be measured for the first time in 3D, as well as precise 3D size distributions. Additional holotomography imaging provided improved spatial resolution (50 nm voxel size), allowing to estimate the probability of finding cracked particles in the as-received material state. The extremely precise 3D shape (including cracks) as well as local chemistry of the particles has been determined. This experiment enabled unprecedented 3D identification of detrimental stress risers relevant for fatigue in as-received aluminium alloys.

Keywords:

• aluminium alloys
• intermetallics
• X-ray tomography
• 3D characterization
• fatigue crack initiation

Acknowledgements

We would like to thank Constellium Technology Centre for providing the material used in this study. We acknowledge the European Synchrotron Radiation Facility for providing beamtime (experiment 1647).

Notes

No potential conflict of interest was reported by the authors.