X-ray topographic investigation of dislocations in titanium single crystals grown by recrystallization

Dislocations in as grown titanium single crystals, produced by recrystallization after phase transformation under high vacuum (5 × 10−10 Torr), are studied by X-ray topography. All kinds of line defects are observed: edge, screw, and helical dislocations, prismatic and glissile loops, sub-boundaries and non-identified defects called “black dots”. Their Burgers' vectors are of a or c + a type. It is established that residual impurities, polishing conditions, and the number of cycle around the phase transformation point α ⇄ β, did not increase the number of defects. Particularly, X-ray topography enables to determine that “black dots” did not appear during polishing but are present in the crystals before.