کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7971840 | 1514613 | 2018 | 46 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
High-temperature internal friction and dynamic moduli in copper
ترجمه فارسی عنوان
اصطکاک داخلی و مدول پویا در مس در دمای بالا
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
دانش مواد (عمومی)
چکیده انگلیسی
New measurements of dynamic shear and Young's moduli and their associated internal frictions were made with torsional and flexural forced-oscillation methods, respectively, on three polycrystalline specimens of pure copper. The tests spanned the 1-1000â¯s range of oscillation periods, at temperatures ranging from those of annealing close to the melting point (1050â¯Â°C) down to room temperature. A broad internal friction peak, found at temperatures around 700â¯Â°C (at 1â¯Hz) for samples annealed at 1050â¯Â°C, is superimposed on a monotonic relaxation background. Non-linear viscoelastic behaviour is observed above strains around 5Ã10â6. The period- and temperature-dependence of both shear modulus and internal friction is adequately captured by an extended “background plus peak” Burgers model for viscoelastic rheology. Activation energies are found to be around 200âkJâmolâ1 for both the high-temperature peak and monotonic damping background, consistent with common diffusional control of both the dissipation background and superimposed peak, plausibly involving stress-induced migration of dislocations. Complementary torsional microcreep tests at selected temperatures reveal that most of the inelastic strain is anelastic (viscous) for loading durations less (greater) than 1000âs. Such linear viscous deformation, observed at low stress in coarse-grained polycrystalline copper, involves much higher strain rates than expected from published rheology, plausibly attributable to the Harper-Dorn mechanism.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Science and Engineering: A - Volume 730, 11 July 2018, Pages 425-437
Journal: Materials Science and Engineering: A - Volume 730, 11 July 2018, Pages 425-437
نویسندگان
Emmanuel C. David, Ian Jackson,