Effect of elastic fields of dislocations of the equilibrium configurations of self-interstitial atoms in cubic crystals. Part I. BCC iron crystal

Conclusion

On the basis of the results from our discussion of the elastic interaction of a selfinterstitial atom with screw and edge dislocations in a bcc iron crystal, we can make the following conclusions.

The interaction of a dislocation with a self-interstitial atom can lead not only to a change in the migration energy of the SIA but also to the stabilization of the SIA configurations that are metastable in the absence of elastic fields.

The region of stabilization of the crowdion configuration and the 〈111〉 dumbbell configuration forms the nearest-neighborhood (r_s≃b) of the screw dislocation, and the axis of the crowdion or the 〈111〉 dumbbell is oriented toward the dislocation line.

The region of stabilization of the crowdion configuration and the 〈111〉 dumbbell configuration in the field of elastic stresses of the edge dislocation is of considerable size (r_e≃5b). The axes of the crowdion configuration and the 〈111〉 dumbbell configuration are oriented in the direction of the Burgers vector b=α/2 [111] of the dislocation.

The elastic field of the edge dislocation stabilizes the crowdion configuration and the 〈111〉 dumbbell configuration in an orientation such as to cause the self-interstitial atom to “hover” at some distance from the dislocation without forming a jog. Subsequent absorption of the self-interstitial atom by the dislocation requires an activation energy greater than the energy of migration of the SIA in the absence of a dislocation.

The coupling energy between the screw dislocation and the crowdion configuration of the self-interstitial atom considerably exceeds the energy of formation of a double kink on the screw dislocation, which ensures activationless slip of screw dislocations because of the interaction with SIAs and, consequently, the radiation softening of bcc iron crystals in the range of sufficiently low temperatures.