FRACTURE PROCESSES IN GERMANIUM
Final rept. 1 June 1961-30 Nov 1962
UTAH UNIV SALT LAKE CITY
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The fracture strength, sigma sub F, of germanium at constant loading rate was determined over a temperature range from -196 to 500 C sigma sub F decreases slowly up to about 200 C, then increases to about 400 C, followed by subsequent decrease. Sigma sub F is found to be essentially independent of ambient for a wide variety of chemical species. These observations are analyzed in terms of fracture nucleation at a flaw near, but not exposed to, the surface, by a presently unknown kinetic process. The role of dislocations apparently is to inhibit fracture by relaxation of stress concentrations up to about 400 C, above which general plastic defor mation precedes fracture, suggesting the possibility of fracture nucleation by dislocation pileus. The applicability of this analysis to another brittle system, Al2O3, is considered in the light of its reported fracture, deformation, wear and friction characteristics. Striking similarities are found in the behavior of these two crystals, suggesting that the underlying mechanisms must have much in common.
- Inorganic Chemistry