3D atom probe study of solute atoms clustering during natural ageing and pre-ageing of an Al-Mg-Si alloy

Abstract

The pair-correlation function applied to 3D Atom Probe reconstructed volumes has been used to study the influence of a pre-ageing treatment (363K) on the early stages of precipitation at 458K in an Al-Mg-Si 6016 alloy. Mg-Si short-range positive pair correlation (clustering) is shown to form after a pre-ageing treatment. The hetero-atomic clusters are thought to act as preferential nucleation sites and lead to a finer dispersion of precipitates after ageing.

Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

“…The average Mg:Si ratio of solute clusters in the T4 condition was 0.6, less than 0.7 in the sample shortly aged for 10 min at 180°C. The low Mg:Si ratio of the solute clusters formed at room temperature appears to be consistent with 13 the strong Si-Si pair correlation as suggested for AA6016 after a long storage at room temperature [10]. In addition, Mg-Si correlation must be significant, otherwise, the Mg:Si ratio of solute clusters will not reach 0.6 > 0.29 of the α-Al grains.…”

“…Failing to address the limitations of the 1DAP analysis makes some previous interpretations about the chemical characteristic of small solute clusters problematic. This may explain why pure Mg and Si clusters were not observed in later 3DAP measurements [6,11] and there are conflictions among different 1DAP results [8][9][10].…”

“…However, the precise nature of solute clusters in Al-Mg-Si wrought Al alloys is far from clear yet, and remains an important topic attracting significant research interests [6,[8][9][10][11]. Previous research using 1D atom probe (1DAP) suggested three types of solute clusters i.e.…”

Clustering in Age‐Hardenable Aluminum Alloys

“…[139] for the alloy 6016 and 60 min natural aging the material already shows positive autocorrelation for Mg-Mg and Si-Si, but not for Si-Mg. Therefore, it was concluded that two distinct populations of clusters form for short RT storage, as already stated in the sequences (9).…”

“…Pair correlation functions were developed for such analyses without recourse to the complexities behind cluster-finding algorithms. [139,140] The similar application of radial distribution functions was investigated for bulk metallic glasses. [141] APT data can provide the means to directly query short range order; for multicomponent alloys, this has been recently formalized.…”