Dislocation nucleation facilitated by atomic segregation

Extended data for 1 2 Dislocation nucleation facilitated by atomic segregation 3

Dislocation nucleation: Diffusive origins.

observed by Meiklejohn and Bean1 (cobalt particles in shells of antiferromagnetic cobalt oxide); both are inhomogeneous and the coexistence of a ferromagnetic and an antiferromagnetic phase gives rise to large exchange bias. This demonstration of tuning the composition of certain Heusler alloys to attain exceptionally high exchange bias fields indicates a route for designing rare-earth-free har...

Elastic criterion for dislocation nucleation

The notion of theoretical strength, the critical stress at which a perfect crystal under uniform loading becomes structurally unstable, is extended to non-uniform loading. A position-dependent defect nucleation criterion has been derived and applied in molecular dynamics (MD) and finite-element simulations of dislocation emission in single-crystal nanoindentation. The resulting measure has the ...

Estimates from atomic models of tension-shear coupling in dislocation nucleation from a crack tip

The normal stress distribution across a slip plane has the effect of reducing the critical loading required for dislocation emission from a crack tip. The reduction by normal stresses was found to be very significant for Si, based on properties estimated for it using density functional theory, to be large for Fe as modeled by the embedded atom method (EAM), and to be smaller in AI, Ni and order...

Dislocation nucleation in bcc Ta single crystals studied by nanoindentation

The study of dislocation nucleation in close-packed metals by nanoindentation has recently attracted much interest. Here, we address the peculiarities of the incipient plasticity in body centered cubic bcc metals using low index Ta single crystals as a model system. The combination of nanoindentation with high-resolution atomic force microscopy provides us with experimental atomic-scale informa...