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In-Situ NMR Study of Dislocation Jump Distance During Creep of Pure and Doped NACL Single Crystals

Published online by Cambridge University Press:  21 February 2011

K. Linga Murty
Affiliation:
North Carolina State University, Raleigh NC 27695-7909
O. Kanert
Affiliation:
University of Dortmund, Postfach 500 500, 46 Dortmund 50, FRG
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Abstract

Nuclear magnetic resonance pulse techniques are used in-situ during creep of single crystals of NaCl to evaluate the contribution of mobile dislocations to spin relaxation. 23Na spin-lattice relaxation rates were measured in the rotating frame (T) during compression creep of single crystals of NaCl along [110] direction at 473K at an applied stress of 20 MPa. The relaxation rates are evaluated from the spin-echo height following π/2, locking and 67° pulse sequence. The height of the free induction decay decreased as soon as the load is applied followed by a gradual increase until the steady-state is reached, at which point a saturation value is observed corresponding to the constant steady-state creep-rate. The mean jump distance of the mobile dislocations, evaluated from the ratio of the signal heights without deformation and during creep, decreased with time/strain reaching a constant value during steady-state creep regime. The results are compared with the dislocation-dislocation spacing, subgrain size as well as the jump distance predicted from creep models. The effects of dilvalent Ca and solid solution with LiCl are examined.

Type
Research Article
Copyright
Copyright © Materials Research Society 1989

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References

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