Influence of the microstructural inhomogeneities on the martensite-to-austenite phase transformation temperatures in TiNiCu-based shape-memory alloys

The morphology and distribution of Ti2Ni precipitates in two batches of Ti-40.8Ni-9Cu (at.%) shape-memory alloys were studied to understand the influence of microstructural inhomogeneities on the martensite-to-austenite phase transformation. Although both batches were produced using nominally identical processing conditions at the same facility, the transformation temperatures were remarkably different. Such behaviour was linked to stereological differences in the precipitates morphology and size distributions, as well as slight differences in the chemical composition.