Inhomogeneity and Anisotropy in Nanostructured Melt-Spun Ti2NiCu Shape-Memory Ribbons

Ti2NiCu exhibits outstanding properties, such as superelasticity. Recently, its functional properties were also demonstrated on the nanoscale, a fact that makes it the preferred choice for numerous applications. Its properties strongly depend on the manufacturing route. In this work, phase analysis, inhomogeneity, and texture of melt-spun Ti2NiCu ribbons were investigated using X-ray diffraction. Initially, the ribbons are amorphous. Passing an electric current result in controlled crystallization. Ribbons with 0%, 60%, and 96% crystallinity were studied. Both B2 austenite and B19 martensite phases were observed. Using grazing incidence X-ray diffraction, the inhomogeneity across the thickness was investigated and found to be substantial. At the free surface, a small presence of titanium dioxide may be present. Pole figures of 60% and 96% crystallinity revealed mostly strong fiber B2 texture in the thickness direction. These observations may be inferred from the manufacturing route. This texture is beneficial. The inhomogeneity across the thickness has to be considered when designing devices.