کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1585857 1514924 2006 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
On the mechanism of crack propagation resistance of fully lamellar TiAl alloy
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد دانش مواد (عمومی)
پیش نمایش صفحه اول مقاله
On the mechanism of crack propagation resistance of fully lamellar TiAl alloy
چکیده انگلیسی

The study was done using notched two-colony thick tensile specimens of a directionally solidified cast fully lamellar TiAl alloy. In-situ observations of fracture processes in scanning electron microscope (SEM) were combined with section-to-section related observations of fracture surfaces to investigate the crack growth process. Finite element method (FEM) calculations are carried out to evaluate the stresses for propagating cracks. The results reveal that: (1) the reason why enhancement of applied load is required to propagate the main crack, was attributed to that the main crack observed at the surface did not extend all the way through the specimen's thickness thus the stress field was still controlled by the notch, in which a definite stress required for extending a crack tip should be kept by increasing the applied load. (2) Crack propagation resistance is enhanced at colony boundaries, only when a change occurs from an inter-lamellar propagation to a trans-lamellar propagation (3) Ligament bridging toughening phenomena can be integrated into aforementioned mechanism. As a whole the processes of new crack nucleation with bridging ligament formation decreases the crack propagation resistance rather than increasing it. (4) In case the majority of microcracks are surface cracks, the effect of microcrack shielding is not obvious.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Science and Engineering: A - Volume 420, Issues 1–2, 25 March 2006, Pages 122–134
نویسندگان
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