The influence of binomial counting statistics on Mg-Si cluster compositions detected by atom probe tomography in naturally aged AlSiMg
File(s)
Published version
Author(s)
Marenzi, Orazio G
Douglas, James O
Kohlhepp, Marius
Hummel, Marc
Gourlay, Christopher M
Type
Journal Article
Abstract
The negative natural ageing (NA) effect, which reduces the strength of heat-treated 6xxx AlMgSi and cast AlSiMg alloys, is commonly attributed to Mg-Si atomic clustering. The reported broadening of Mg-Si cluster compositions at small cluster sizes has supported several proposed mechanisms for this effect. This work examines the extent to which the apparent compositional broadening arises from binomial counting statistics rather than real compositional variation. 3719 clusters identified by atom probe tomography (APT) in a NA AlSi10Mg high-pressure die casting were analysed and compared with synthetic datasets and binomial predictions. The observed compositional spread is quantitatively reproduced by an overdispersed binomial distribution, where the overdispersion is not a function of cluster size, requiring a reassessment of mechanisms linking cluster composition broadening to the negative-NA effect. The findings show the results of APT-clustersearches can be misleading without statistical context, with expected relevance to the general study of nanoscale-clustering by APT.
Date Issued
2026-10-01
Date Acceptance
2026-06-16
Citation
Scripta Materialia, 2026, 283
ISSN
1359-6462
Publisher
Elsevier BV
Journal / Book Title
Scripta Materialia
Volume
283
Copyright Statement
© 2026 The Author(s). Published by Elsevier Inc. on behalf of Acta Materialia Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
License URL
Publication Status
Published
Article Number
117450
Date Publish Online
2026-06-18