کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10620624 | 988645 | 2011 | 16 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Effects of Li additions on precipitation-strengthened Al-Sc and Al-Sc-Yb alloys
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Two Al-Sc-based alloys (Al-0.12Sc and Al-0.042Sc-0.009Yb, at.%) and their counterparts with Li additions (Al-2.9Li-0.11Sc and Al-5.53Li-0.048Sc-0.009Yb, at.%) are aged at 325 °C. For both base alloys, the addition of Li results in greater peak hardness from incorporation of Li in the L12-structured αâ²-Al3(Sc,Li) and αâ²-Al3(Sc,Li,Yb) precipitates, and a concomitant increase in number density and volume fraction of the precipitates and a reduction in their mean radius. These changes result from a combination of: (i) an increase in the driving force for precipitate nucleation due to Li; (ii) a decrease in the elastic energy of the coherent misfitting precipitates from a decrease in their lattice parameter mismatch due to their Li content; and (iii) a decrease in the interfacial free energy, as determined from measurements of the relative Gibbsian interfacial excess of Li. In Al-2.9Li-0.11Sc (at.%), the Li concentration of the precipitates decreases from 9.1 at.% in the peak-aged state (8 h) to 5.7 at.% in the over-aged state (1536 h). As a result, the precipitate volume fraction decreases from 0.56% at peak aging time to 0.45% at 1536 h. In Al-5.53Li-0.048Sc-0.009Yb (at.%), the relatively limited Li concentration produces only a small increase in Vickers microhardness from precipitation of metastable δâ²-Al3Li upon a second aging at 170 °C following the primary aging at 325 °C.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Acta Materialia - Volume 59, Issue 4, February 2011, Pages 1700-1715
Journal: Acta Materialia - Volume 59, Issue 4, February 2011, Pages 1700-1715
نویسندگان
M.E. Krug, D.C. Dunand, D.N. Seidman,