The martensitic-transformation in polycrystalline Ti-50.3 at pct. Ni alloy has been investigated using the technique of transmission-electron microscopy and diffraction. It was found that the extra reflections observed in the high temperature phase (CsCl, B2 type structure) are not related to the martensitic-transformation but are most likely associated with very fine ordered particles (less than 100Å) of a Ni-rich phase, which is coherent with the CsCl-structure. The streaming or shimmering effects observed in bright-field images of a number of alloys which undergo martensitic-transformation and have sometimes been interpreted as a manifestation of lattice oscillations, were not observed in the present investigation.
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