FIG. 3. (a) Defect configurations involving two (X − W)W mixed–interstitials in which X corresponds to V, Ti and Re atoms. The figure shows a slice parallel to a {110} plane of the structure. Small (blue) spheres indicate tungsten atoms whereas large (gray) spheres indicate X atoms. Thicker (yellow) cylinders indicate bond lengths shorter than 2.3 °A whereas thinner (gray) cylinders indicate bond lengths shorter than 2.5 °A. (b) An illustration of parallel h111i strings in BCC tungsten. (c) Binding energy of a pair of titanium bridge mixed–interstitial with respect to string number.

FIG. 3. (a) Defect configurations involving two (X − W)W mixed–interstitials in which X corresponds to V, Ti and Re atoms. The figure
shows a slice parallel to a {110} plane of the structure. Small (blue) spheres indicate tungsten atoms whereas large (gray) spheres indicate
X atoms. Thicker (yellow) cylinders indicate bond lengths shorter than 2.3 °A whereas thinner (gray) cylinders indicate bond lengths shorter
than 2.5 °A. (b) An illustration of parallel h111i strings in BCC tungsten. (c) Binding energy of a pair of titanium bridge mixed–interstitial with
respect to string number.