Studies of the R-phase transformation in a Ti-51at.%Ni alloy by transmission electron microscopy

The R-phase transformation in a Ti-51at.%Ni shape memory alloy was studied by transmission electron microscopy (TEM) including high resolution microscopy and in situ observations at cooling. The incommensurability of the superlattice reflections was examined by recording the diffraction patterns with the use of a CCD slowscan camera and analysing the reflection positions by DigitalMicrograph program. It is shown that the incommensurability exists in this alloy within a wide temperature range and its is neither regular nor periodic. It decreases with decreasing temperature reaching finally the commensurate R-phase state