کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7978566 | 1514715 | 2015 | 49 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
On the role of Re in the stress and temperature dependence of creep of Ni-base single crystal superalloys
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
دانش مواد (عمومی)
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
In the present study we investigate the creep behavior of a Ni-base single crystal superalloy. We evaluate the stress and temperature dependence of the minimum creep rate, which shows a power law type of stress dependence (characterized by a stress exponent n) and an exponential type of temperature dependence (characterized by an apparent activation energy Qapp). Under conditions of high temperature (1323Â K) and low stress (160Â MPa) creep, n and Qapp are determined as 5.3 and 529Â kJ/mol, respectively. For lower temperatures (1123Â K) and higher stresses (600Â MPa) the stress exponent n is higher (8.5) while the apparent activation energy of creep is lower (382Â kJ/mol). We show that there is a general trend: stress exponents n increase with increasing stress and decreasing temperature, while higher apparent activation energies are observed for lower stresses and higher temperatures. We use density functional theory (DFT) to calculate the activation energy of diffusion for Re in a binary Ni-Re alloy with low Re-concentrations. The resulting energy is almost a factor 2 smaller than the apparent activation energy of creep. We explain why it is not straightforward to rationalize the temperature dependence of creep merely on the basis of the diffusion of one alloying element. We show that the evolution of the microstructure also must be considered.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Science and Engineering: A - Volume 628, 25 March 2015, Pages 382-395
Journal: Materials Science and Engineering: A - Volume 628, 25 March 2015, Pages 382-395
نویسندگان
P. Wollgramm, H. Buck, K. Neuking, A.B. Parsa, S. Schuwalow, J. Rogal, R. Drautz, G. Eggeler,