Atomistic simulation of dislocation nucleation and motion from a crack tip
- Argonne National Lab., IL (United States). Materials Science Div.
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Nuclear Engineering
A recently developed fully atomistic technique for fracture simulations is applied to the study of dislocation emission from a crack tip in an elastically anisotropic f.c.c. crystal. The detailed atomic-scale mechanisms of dislocation nucleation and motion are investigated as a function of the external load. Analysis of the atomic configurations around the crack tip demonstrates an intimate coupling of the nucleating dislocation with a step formed at the crack surface. Displacement and stress fields around both nucleating and moving dislocations are compared to the predictions of the Peierls-Nabarro continuum-elastic model by Rice. The size of a nucleating (incipient) dislocation is found to be larger than that of a fully-formed dislocation. Also, the authors elucidate the reasons why the value of the unstable-stacking energy estimated by means of the rigid-block sliding concept, a feature common to several continuum-elastic models, overestimates the activation energy for dislocation nucleation. They conclude that the concept of unstable-stacking energy should be replaced by the true energy barrier for dislocation nucleation, incorporating the full inhomogeneity of the displacement field.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- Sponsoring Organization:
- USDOE, Washington, DC (United States); North Atlantic Treaty Organization, Brussels (Belgium)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 599698
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 12 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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