Soft X-ray XAFS Analysis of Cluster Formation Behavior during Natural Aging on an Al–Mg–Si Alloy

Abstract

This study investigated cluster formation in the early stages of natural aging in Al1.04 mass%Si0.55 mass%Mg alloys by soft X-ray XAFS measurements and first-principles calculation. XAFS measurements at the Mg-K and Si-K edges were carried out at the BL27SU beamline at SPring-8. It was found that the absorption edge energies changed as aging proceeded. Density functional theory (DFT) calculations were used to determine the valence electron densities near Si and Mg atoms and to simulate the Si-K and Mg-K edge spectra for some cluster models. On the basis of the results, it was demonstrated that Si and Mg atoms formed clusters in four stages (IIV) during natural aging. In stage I, Si-vacancy pairs, Mg-vacancy pairs, and a combination of both were formed. In stage II, vacancies were released from the clusters formed in stage I. In stage III, Mg-vacancy pairs were included in the clusters. In stage IV, the clusters coarsened through the release of vacancies. These results indicate that soft X-ray XAFS, which is capable of identifying individual elements, has the ability to provide information on such clusters.

Best Papers Awarded by JILM and JSTP in <i>Materials Transactions</i>

“…2 XANES spectra near Si-K edge of Al-Mg-Si alloys and reference samples. 2) was different from the thermodynamic calculations using the existing database, whereas such a result was found in conventional Al-Mg-Zn-Cu alloys. 33,34) The added Ni element enhanced the formation of the fine Al 3 Ni phase located at grain boundaries (Fig.…”

“…We are pleased to introduce the best papers awarded by The Japan Institute of Light Metals (JILM) and The Japan Society for Technology of Plasticity (JSTP). [1][2][3][4][5][6] Materials Transactions publishes papers from 14 institutes and societies where JILM and JSTP are two active companions [https:// jimm.jp/en/publications/journal.html]. Authors may submit papers through either one of the 14 institutes and societies depending on the specialties in terms of materials, analytical procedures and processing technologies, although some institutes and societies accept the submission only from members including expected members.…”

“…In this article as a current trend in research, the six best papers were introduced, [1][2][3][4][5][6] which were selected from cutting edge research in JILM and JSTP: three best papers are from each of JILM and JSTP and two out of the three in JILM 2,3) are for young scientists in JILM.…”

“…The selection of the three best papers in JILM [1][2][3] was made in two-step processes: first through a recommendation committee and second through an evaluation committee. The members in the recommendation committee nominates around 10 papers out of all the papers published through JILM in the past one year.…”

“…Here, the six awarded papers [1][2][3][4][5][6] are introduced below with brief summaries provided by the corresponding authors. Many experimental studies on diffusion in titanium-based binary alloys containing ¡or ¢-stabilizing elements have been performed.…”