Calculation of the interaction energy between a self-interstitial and a (1/2)⟨111⟩ screw dislocation in b.c.c. transition metals moments approach

Abstract

Abstract The interaction between a self-interstitial and a (1/2)⟨111⟩ screw dislocation in b.c.c. transition metals (α-Fe, Nb and W) has been investigated in detail using a tight-binding-type electronic theory. The repulsive core–core interaction energies are simulated by a Born–Mayer potential as well as by a simple power law potential. The interstitial-screw dislocation interaction energies are calculated for the ⟨110⟩ and ⟨111⟩ split interstitials as a function of their relative location and orientation with respect to the dislocation. The calculated binding energies for the ⟨110⟩ and ⟨111⟩ type interstitials in α-Fe are of the order of 0·28 and 0·66 eV respectively. In general, it is found that the interstitial-screw dislocation interaction is important for the ⟨111⟩ type interstitials and its magnitude is comparable to the double-kink nucleation energy. Furthermore, it is shown that the present results for the interstitial-screw dislocation interaction can account for the orientation dependence of the irradiation softening observed for the b.c.c. transition metals (α-Fe and Nb).