کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10714058 | 1025568 | 2012 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Study of ageing in Al-Mg-Si alloys by positron annihilation spectroscopy
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک ماده چگال
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Study of ageing in Al-Mg-Si alloys by positron annihilation spectroscopy Study of ageing in Al-Mg-Si alloys by positron annihilation spectroscopy](/preview/png/10714058.png)
چکیده انگلیسی
In many common Al-Mg-Si alloys (6000 series) intermediate storage at or near 'room temperature' after solutionising leads to pronounced changes of the precipitation kinetics during the ensuing artificial ageing step at â180 °C. This is not only an annoyance in production, but also a challenge for researchers. We studied the kinetics of natural 'room temperature' ageing (NA) in Al-Mg-Si alloys by means of various different techniques, namely electrical resistivity and hardness measurement, thermoanalysis and positron lifetime and Doppler broadening (DB) spectroscopy to identify the stages in which the negative effect of NA on artificial ageing might appear. Positron lifetime measurements were carried out in a fast mode, allowing us to measure average lifetimes in below 1 min. DB measurements were carried out with a single detector and a 68Ge positron source by employing high momentum analysis. The various measurements show that NA is much more complex than anticipated and at least four different stages can be distinguished. The nature of these stages cannot be given with certainty, but a possible sequence includes vacancy diffusion to individual solute atoms, nucleation of solute clusters, Mg agglomeration to clusters and coarsening or ordering of such clusters. Positron lifetime measurements after more complex ageing treatments involving storage at 0 °C, 20 °C and 180 °C have also been carried out and help to understand the mechanisms involved.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physica B: Condensed Matter - Volume 407, Issue 14, 15 July 2012, Pages 2689-2696
Journal: Physica B: Condensed Matter - Volume 407, Issue 14, 15 July 2012, Pages 2689-2696
نویسندگان
J. Banhart, M. Liu, Y. Yong, Z. Liang, C.S.T. Chang, M. Elsayed, M.D.H. Lay,