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Dislocation dynamics in Al–Mg–Zn alloys: A nuclear magnetic resonance and transmission electron microscopic study

Published online by Cambridge University Press:  31 January 2011

J. Th. M. De Hosson
Affiliation:
Department of Applied Physics, Materials Science Centre, University of Groningen, Nijenborgh 18, 9747 AG Groningen, The Netherlands
O. Kanert
Affiliation:
Institute of Physics, University of Dortmund, 46 Dortmund 50, Federal Republic of Germany
U. Schlagowski
Affiliation:
Institute of Physics, University of Dortmund, 46 Dortmund 50, Federal Republic of Germany
G. Boom
Affiliation:
Department of Applied Physics, Materials Science Centre, University of Groningen, Nijenborgh 18, 9747 AG Groningen, The Netherlands
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Abstract

Pulsed nuclear magnetic resonance (NMR) proved to be a complementary new technique for the study of moving dislocations in Al–Mg–Zn alloys. The NMR technique, in combination with transmission electron microscopy (TEM), has been applied to study dislocation motion in Al–0.6 at. % Mg–1 at. % Zn and Al–2 at. % Mg–2.5 at. % Zn. Spin-lattice relaxation measurements clearly indicate that fluctuations in the nuclear quadrupolar interactions caused by moving dislocations in Al–Mg–Zn are different compared to those in ultra pure Al. From the motion induced part of the spin-lattice relaxation rate the mean jump distance of mobile dislocations has been determined as a function of strain. From the NMR data it is concluded that moving dislocations advance over a number of solute atoms in these alloys as described by Mott-Nabarro's model. At large strains there exists a striking difference between the mean jump distances in Al–0.6 at. % Mg–1 at. % Zn and in Al–1.2 at. % Mg–2.5 at. % Zn. The latter is about five times smaller than the former one. This is consistent with TEM observations that show dislocation cell formation only in Al–0.6 at. % Mg-1 at. % Zn and the macroscopic stress-strain dependences of these alloys.

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Articles
Copyright
Copyright © Materials Research Society 1988

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References

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