Influence of Orientation on Properties of Grain Boundaries in NaCl

Autor: N. Fuschillo, A. D. McMaster, M. L. Gimpl
Rok vydání: 1968
Předmět:
Zdroj: Journal of the American Ceramic Society. 51:655-660
ISSN: 1551-2916
0002-7820
DOI: 10.1111/j.1151-2916.1968.tb12639.x
Popis: Simple (100) tilt, twist, and double-tilt bicrystals of NaCl, grown by the Kyropoulos technique from melts of high-purity NaCl, alone and with controlled impurity additions, were examined for mechanical strength and structure of the grain boundaries. Grain boundary fracture strengths, measured in three-point bending, showed that high-purity bicrystals with simple tilt orientations were stronger than those with simple twist at high mismatch angles (37° to 45°). The results did not show a functional dependence of strength on angle of mismatch in either tilt or twist bicrystals. Pips observed on parted grain boundaries of high-purity NaCl (100] twist and double-tilt bicrystals were believed to represent regions of continuity across the boundary. This feature was rare in similar-purity NaCl (100) tilt bicrystals. Separate additions of 100 ppm SiO2, CaCl2, FeCls, and KCl to the melt had no apparent effect on the character of the grain boundary. However, an addition of 1000 ppm CaCl2 nearly doubled the strength of a (1001) 30° twist bicrystal, whereas the same addition weakened a (100) 45° tilt bicrystal. Sodium chloride (100) tilt grain boundaries, examined in situ under dark-field illumination, showed randomly distributed spots, believed to be impurity segregations, with their maximum density at the boundary. The spot densities increased with increasing tilt angle for angles of 15° and greater. The spots were not observed in the low-angle tilt boundaries (
Databáze: OpenAIRE
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