X-ray study of martensitic transformation in titanium nickelide single crystal

The distribution of the orientations of the B19′-martensite crystals formed upon cooling in the single crystal B2-phase of the Ti–51 at.% Ni alloy has been studied. To this end, positions of the (0 0 2), (1,1,−1), (0 2 0), and (1 1 1) planes of the B19′-martensite, which “originated” from the (1 1 0) plane of the B2-phase, were determined. It was found that the results obtained could be described using the conventional monoclinic crystal structure of the B19′-martensite and the orientation relationships obtained earlier. However, a small deviation from the parallelism between the (0 2 0)B19′ and (1 1 0)B2 planes is observed. Upon the transformation of the single crystal B2-phase into the B19′-martensite in cooling, no less than 12 crystallographically equivalent orientations of martensitic crystals are realized in the irradiated volume of 1.5 mm × 3 mm × 0.01 mm. The realization of various orientations of this martensite is equiprobable. The B19′-martensite has monoclinic angles from 90° to 96.8°.