Title: Crack dislocation interactions in ionic crystals with rock-salt structure

Authors: K. Higashida, N. Narita

Addresses: Department of Materials Science and Engineering, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan. ' Department of Materials Science and Engineering, Kyushu Institute of Technology, Tobata-ku, Kitakyushu 804-8550, Japan

Abstract: The modification of the local stress intensity factor due to dislocations near a crack tip has been analysed using 2-D and 3-D potential function methods. Observations of dislocation configurations in ionic crystals with a rock-salt structure have also been made using the etch-pit technique, photoelasticity and high-voltage electron microscopy (HVEM). In thick crystals, hinge-type structures of slip bands were formed along {100} planes ahead of a {100} crack, while in thin crystals dislocation structures corresponding to the 45°-shear-type plastic zone were commonly observed. Based on the observed geometry of the crack tip dislocations, interactions between a crack and dislocations were calculated, and it was found that mode I shielding was induced by the dislocations in both structures.

Keywords: crack dislocation; fracture toughness; HVEM; shielding; ionic crystals; rock salt structure; stress intensity factors; crack tip.

DOI: 10.1504/IJMPT.1999.036271

International Journal of Materials and Product Technology, 1999 Vol.14 No.2/3/4, pp.259 - 271

Published online: 01 Nov 2010 *

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