Dislocation nucleation facilitated by atomic segregation

doi:10.1038/NMAT5034

Dislocation nucleation facilitated by atomic segregation

2017-11-27

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DOI：10.1038/NMAT5034

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Abstract

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Surface segregation-the enrichment of one element at the surface, relative to the bulk-is ubiquitous to multi-component materials. Using the example of a Cu-Au solid solution, we demonstrate that compositional variations induced by surface segregation are accompanied by misfit strain and the formation of dislocations in the subsurface region via a surface diffusion and trapping process. The resulting chemically ordered surface regions acts as an effective barrier that inhibits subsequent dislocation annihilation at free surfaces. Using dynamic, atomic-scale resolution electron microscopy observations and theory modelling, we show that the dislocations are highly active, and we delineate the specific atomic-scale mechanisms associated with their nucleation, glide, climb, and annihilation at elevated temperatures. These observations provide mechanistic detail of how dislocations nucleate and migrate at heterointerfaces in dissimilar-material systems.

Keywords:

MOLECULAR-DYNAMICS

STRAIN RELAXATION

THIN-FILMS

CU-AG

TEMPERATURE

POTENTIALS

SIMULATION

METALS

SYSTEM

COPPER

Dislocation nucleation facilitated by atomic segregation

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