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Proceedings Paper

Masurement Of Dislocation Velocities In Potassium Chloride Single Crystals From Dynamic Localised Loading Experiments
Author(s): M. Munawar Chaudhri
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Paper Abstract

Freshly cleaved {100} faces of potassium chloride crystals were impacted at normal incidence with glass and tungsten carbide spheres of diameter 0.4 and 0.7 mm, respectively, and of velocities of up to 200 m s-1. This caused the plastic flow and a system of fractures at the impact site; one such system is generated by the interactions of screw dislocations on {100}45 planes inclined to the impacted plane at 45°. The extent of these cracks has been shown to be almost the same as that of the boundary of the plastically deformed region. Therefore the movement of this system of cracks directly gives us information about the velocity of the dislocation front, thus providing us with a new method of monitoring the dislocation velocities. High-speed framing microphotography using a Beckman and Whitley model 189 rotating mirror camera working at a rate of - 2 million frames per second has been successfully used to follow the propagation of these cracks. The maximum velocity of the dislocations was found to be 700 m s-1 corresponding to a shear stress of - 8 MPa. The dislocations only propagated during the loading part of the impact, and their velocity was linearly dependent on the shear stress.

Paper Details

Date Published: 1 February 1985
PDF: 5 pages
Proc. SPIE 0491, 16th Intl Congress on High Speed Photography and Photonics, (1 February 1985);
Show Author Affiliations
M. Munawar Chaudhri, Cavendish Laboratory (UK)

Published in SPIE Proceedings Vol. 0491:
16th Intl Congress on High Speed Photography and Photonics
Michel L. Andre; Manfred Hugenschmidt, Editor(s)

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