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Simulation of Dislocation Dynamics in Ni3Al: A Study of Velocity Autocorrelations

Published online by Cambridge University Press:  15 February 2011

C. K. Erdonmez  and
D. C. Chrzan
C. K. Erdonmez
Affiliation:
Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720
D. C. Chrzan
Affiliation:
Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720
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Abstract

The yield strength anomaly in some L12 compounds has been linked to the thermally assisted cross slip of screw superdislocations. This work continues earlier efforts to understand the yield strength anomaly in L12 alloys using computer simulations of dislocation motion. Dislocations are modelled within isotropic elasticity theory, and simple rules are used to model the cross-slip process in the two dimensional geometry of the simulation. The velocity of a single dislocation in Ni3Al is studied as a function of the applied stress. The observed velocities vary nonlinearly with the applied stress. Further, dislocations are observed to become immobile for small applied loads. At high stresses, the dislocations are observed to advance relatively unhindered by the thermally activated cross slip process. Fluctuations in the velocity of the dislocations are studied, and their autocorrelation function shows an increased correlation time near a threshold stress. This threshold stress is identified with the critical stress proposed in earlier works.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 578: Symposia A/C – Multiscale Phenomena in Materials - Experiments in Modeling , 1999 , 143
Copyright
Copyright © Materials Research Society 2000

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References

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