Linking a completely three-dimensional nanostrain to a structural transformation eigenstrain.

Ni-Ti is one of the most popular shape-memory alloys, a phenomenon resulting from a martensitic transformation. Commercial Ni-Ti-based alloys are often thermally treated to contain Ni(4)Ti(3) precipitates. The presence of these precipitates can introduce an extra transformation step related to the so-called R-phase.

High-quality sample preparation by low kV FIB thinning for analytical TEM measurements.

Focused ion beam specimen preparation has been used for NiTi samples and SrTiO3/SrRuO3 multilayers with prevention of surface amorphization and Ga implantation by a 2-kV cleaning procedure. Transmission electron microscopy techniques show that the samples are of high quality with a controlled thickness over large scales. Furthermore, preferential thinning effects in multicompounds are avoided, which is important when analytical transmission electron microscopy measurements need to be interpreted in a quantitative manner.

Cross-section transmission electron microscopy characterization of the near-surface structure of medical Nitinol superelastic tubing.

The application of Nitinol in a wide variety of medical implants is progressively increasing because of its unique mechanical properties, durability and biocompatibility. However, as Nitinol consists of about 50 at.% of toxic Ni, certain applications are still hindered by the concern of free Ni release in the surrounding tissue.

Electron-diffraction structure refinement of Ni4Ti3 precipitates in Ni52Ti48.

The atomic coordinates of the crystal structure of nanoscale Ni4Ti3 precipitates in Ni-rich NiTi is refined by means of a least-squares method based on intensity measures of electron-diffraction patterns. The optimization is performed in combination with density functional theory calculations and has yielded an R\bar 3 symmetry with slightly different atomic positions when compared with the existing structure. The new unit cell offers a better understanding of the lattice deformation from the B2 matrix.