کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10620427 988622 2011 16 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Superior fatigue crack growth resistance, irreversibility, and fatigue crack growth-microstructure relationship of nanocrystalline alloys
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Superior fatigue crack growth resistance, irreversibility, and fatigue crack growth-microstructure relationship of nanocrystalline alloys
چکیده انگلیسی
While previous studies have reported that nanocrystalline materials exhibit poor resistance to fatigue crack growth (FCG), the electro-deposited nanocrystalline Ni-Co alloys tested in this paper show superior resistance to FCG. The high damage tolerance of our alloy is attributed to the following: alloying with Co, low internal stresses resulting in stability of the microstructure, and a combination of high strength and ductility. The high density of grain boundaries interact with the dislocations emitted from the crack tip, which impedes FCG, as predicted by the present model and measured experimentally by digital image correlation. Further, the addition of Co increases the strength of the material by refining the grain size, reducing the fraction of low angle grain boundaries, and reducing the stacking fault energy of the material, thereby increasing the prevalence of twinning. The microstructure is stabilized by minimizing the internal stress during a stress relief heat treatment following the electro-deposition process. As a result grain growth does not occur during deformation, leaving dislocation-mediated plasticity as the primary deformation mechanism. The low internal stresses and nanoscale twins preserve the ductility of the material, thereby reaching a balance between strength and ductility, which results in a superior resistance to FCG.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Acta Materialia - Volume 59, Issue 19, November 2011, Pages 7340-7355
نویسندگان
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