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Observation of Blunting and Jogging Dislocation Emission at Crack Tips in Alkali Halide Single Crystals

Published

Author(s)

Timothy J. Foecke, W Gerberich

Abstract

Bulk observations of crack tip dislocation emission in NaC1 and KC1 have been made in both blunting and jogging orientations. Measurements of the critical stress intensity for dislocation emission in model I (KIe) have been made for both materials in both orientations. It was seen that emission progressed by the formation of several discrete slip bands at various locations along the crack front, these bands consisting of concentric loops. The pileup of leading edge components of the loops were observed during deformation using optical birefringenece techniques. It was found that the measured values of KIe were a factor or three below the predictions of the Rice-Thomson theory for crack tip dislocation emission. It was further found that jogging and blunting emission often occurred simultaneously, and that the value of KIe for jogging emission was somewhat less than that for blunting emission, when the limitations on the resolution of the experiment in each orientation were taken into account.
Citation
Journal of Materials Research

Keywords

crack tip, dislocation, emission, KC1, NaC1

Citation

Foecke, T. and Gerberich, W. (2008), Observation of Blunting and Jogging Dislocation Emission at Crack Tips in Alkali Halide Single Crystals, Journal of Materials Research (Accessed February 24, 2024)
Created October 16, 2008