Title

Crack tip plasticity: overview of crack-dislocations interactions

Crack tip plasticity: overview of crack-dislocations interactions

Authorship

MICHOT, GÉRARD

MICHOT, GÉRARD

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DOI

10.5151/2594-5327-C00254-3932-3953

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Abstract

In the present paper the influence of a plastic zone developed at crack tip on the reinforcement of the material is emphasised. The mechanical interaction is described on the microscopic scale in terms of crack shielding by dislocations. In semi-brittle materials plastic deformation at crack tip is first negligible in the brittle range and then increases up to full relaxation in the plastic range. Such a transition is readily explained through a mechanism controlled by dislocation mobility but large shifts in the transition temperature can result from differences in dislocation source activities. In materials containing bulk sources, "stimulated emission" rather than spontaneous nucleation is likely to occur at crack tip.

In the present paper the influence of a plastic zone developed at crack tip on the reinforcement of the material is emphasised. The mechanical interaction is described on the microscopic scale in terms of crack shielding by dislocations. In semi-brittle materials plastic deformation at crack tip is first negligible in the brittle range and then increases up to full relaxation in the plastic range. Such a transition is readily explained through a mechanism controlled by dislocation mobility but large shifts in the transition temperature can result from differences in dislocation source activities. In materials containing bulk sources, "stimulated emission" rather than spontaneous nucleation is likely to occur at crack tip.

Keywords

dislocation, shielding, brittle to ductile transition, plastic zone, crack tip

dislocation, shielding, brittle to ductile transition, plastic zone, crack tip