<i>μ</i>SR study of Al-0.67%Mg-0.77%Si alloys

Nishimura, K.; Matsuda, Kenji; Komaki, R; Nunomura, Norio; Wenner, Sigurd; Holmestad, Randi; Matsuzaki, Takashi; Watanabe, Isao; Pratt, F. L.; Marioara, Calin Daniel

doi:10.1088/1742-6596/551/1/012031

Cited by 9 publications

(7 citation statements)

References 20 publications

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“…We checked that the difference between the fit and the tabulated rate was less than 5%. The rates of 17 O(α, γ), 17 O(α, n), 22 Ne(α, γ), and 22 Ne(α, n) are still uncertain in the range of temperature of interest for the s-process in massive stars (e.g Best et al 2011;Nishimura et al 2014). Figure 1 compares the different available rates in the literature for these four reactions.…”

Section: Input Parametersmentioning

confidence: 99%

Non-standard s-process in massive rotating stars

Choplin

Hirschi

Meynet

et al. 2018

A&A

108

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Context. Recent studies show that rotation significantly affects the s-process in massive stars. Aims. We provide tables of yields for non-rotating and rotating massive stars between 10 and 150 M at Z = 10 −3 ([Fe/H] = −1.8).Tables for different mass cuts are provided. The complete s-process is followed during the whole evolution with a network of 737 isotopes, from hydrogen to polonium. Methods. A grid of stellar models with initial masses of 10, 15, 20, 25, 40, 60, 85, 120, and 150 M and with an initial rotation rate of both 0% or 40% of the critical velocity was computed. Three extra models were computed in order to investigate the effect of faster rotation (70% of the critical velocity) and of a lower 17 O(α, γ) reaction rate. Results. At the considered metallicity, rotation has a strong impact on the production of s-elements for initial masses between 20 and 60 M . In this range, the first s-process peak is boosted by 2−3 dex if rotation is included. Above 60 M , s-element yields of rotating and non-rotating models are similar. Increasing the initial rotation from 40% to 70% of the critical velocity enhances the production of 40 Z 60 elements by ∼0.5−1 dex. Adopting a reasonably lower 17 O(α, γ) rate in the fast-rotating model (70% of the critical velocity) boosts again the yields of s-elements with 55 Z 82 by about 1 dex. In particular, a modest amount of Pb is produced. Together with s-elements, some light elements (particularly fluorine) are strongly overproduced in rotating models.

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Section: Input Parametersmentioning

confidence: 99%

Non-standard s-process in massive rotating stars

Choplin

Hirschi

Meynet

et al. 2018

A&A

108

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“…There is, however, a clear discontinuity in the tendencies around 120 K. According to the previous studies for Al-Mg-Si alloys [7][8][9][10], muons tended to be trapped in high density shallow electrical potentials produced by Mg atoms in lower temperature range below 120 K, and vacancy associated clusters caught muons in the higher temperature region. The number density of randomly distributed Mg atoms is on the order of 10 26 m -3 , but that of the clusters associated with vacancy is considered to be approximately 1 x 10 24 m -3 [12].…”

Section: Figs 3(a)-3(d)mentioning

confidence: 84%

“…Recently, we have successfully studied heat treatment effects on the Mg/Si/vacancy clusters in Al-Mg-Si (6000 series) alloys by the zero-field muon spin relaxation spectroscopy [7][8][9][10]. Al-Mg-Si alloys are known to be quite sensitive to the aging process, including natural aging (stored at room temperature).…”

Section: Introductionmentioning

confidence: 99%

Muon Spin Relaxation of an Al–3.4%Zn–1.9%Mg alloy

Nishimura

Matsuda

Nunomura

et al. 2018

Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (ΜSR2017)

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Zero-field muon spin relaxation measurements were carried out on an Al-3.4% Zn-1.9% Mg alloy in the temperature range from 10 to 300 K. A sample heat treatment clearly made an effect on the relaxation rates of Al-3.4% Zn-1.9% Mg alloys; the dipole width and trapping rate of the heat-treated sample were smaller than those of the non-treated sample below 140 K. The temperature dependence of the trapping and detrapping rates was used to estimate activation energies of muons in Al-3.4% Zn-1.9% Mg.

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“…From the various studies with Al-Mg-Si alloys, vacancy behavior is considered to play an important role in the aging process, stimulating diffusion of solute Mg and Si atoms and nucleation of clusters. Positron annihilation spectroscopy (PAS) [6][7][8][9] and muon spin relaxation spectroscopy (μSR) [22][23][24] have been successfully used to investigate the vacancy and clustering behavior in Al-Mg-Si alloys. These methods, however, are not widely accessible as special facilities and equipment are required to handle radioactive materials.…”

Section: Introductionmentioning

confidence: 99%

Early Stage Clustering Behavior in Al-Mg-Si Alloys Observed via Time Dependent Magnetization

et al. 2016

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Time dependent magnetization of Al-0.67 at.%Mg-0.73 at.%Si, Al-1.07 at.%Mg-0.33 at.%Si and Al-1.07 at.%Mg-0.53 at.%Si alloys are presented over a range of constant temperatures between 250 and 320 K. The magnetization vs. time curves for the samples show minima for temperatures near 290 K. The observed times at which the magnetization minima occur were found to depend on both the solute concentrations and the measurement temperatures. From these results the activation energies from the Si-rich clustering stage to the Mg-Si co-clustering stage were extracted. The deduced activation energies were found to be comparable to those from the positron annihilation measurements, depending on the solute concentrations.

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μSR study of Al-0.67%Mg-0.77%Si alloys

Cited by 9 publications

References 20 publications

Non-standard s-process in massive rotating stars

Non-standard s-process in massive rotating stars

Muon Spin Relaxation of an Al–3.4%Zn–1.9%Mg alloy

Early Stage Clustering Behavior in Al-Mg-Si Alloys Observed via Time Dependent Magnetization

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