Mechanism of diffusion-controlled brittle fracture
Two generation of UHV testing systems were developed, one for testing pre-cracked specimens at constant displacement and the other at constant load, and they were supplemented by a computer-controlled potential-drop system for measurement of crack-growth rates. The latter system was also developed during this project. Experiments were carried out on the alloy Cu-8%Sn which was used as a model system for the phenomenon of diffusion-controlled fracture by intergranular decohesion resulting from the ingress of an embrittling element from a free surface as the result of an applied stress. The cracking phenomenon found earlier in alloy steels, and shown to be due to surface-adsorbed sulfur, was reproduced in the Cu-Sn alloy. This provided verification of the earlier proposed mechanism for the cracking phenomenon in the alloy steels, known as stress-relief cracking, and it also provided support for the hypothesis that the phenomenon was of a generic nature. In conjunction with the experimental work, the development of a quantitative theory of this class of brittle fracture, which we have termed dynamic embrittlement,'' was begun.
- Research Organization:
- Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-87ER45290
- OSTI ID:
- 5635597
- Report Number(s):
- DOE/ER/45290-5; ON: DE92011572
- Country of Publication:
- United States
- Language:
- English
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Quasi-static intergranular cracking in a Cu-Sn alloy: An analog of stress relief cracking of steels
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