In-situ martensite texture evolution and phase fractions of superelastic NiTi upon tensile loading using synchrotron hard x-ray diffraction

von Mahamudul Hasan

104 Seiten, Buch

Kurzbeschreibung des Verlags

This work investigated the martensite texture evolution in superelastic Ni-rich NiTi flat tensile specimens upon uniaxial tensile loading along the rolling direction (RD) and the transverse direction (TD) and also in NiTi wire upon loading along the drawing direction (DD) using high-energy synchrotron x-ray diffraction in transmission geometry. High-energy x-ray diffraction is an adequate tool to capture crystallographic information such as phase state and local texture evolution in bulk. Texture information is identified from the intensity variations along Debye-Scherrer rings recorded on area detector diffraction images. The original textures of the cold rolled B2 austenite and that of the stress-induced B19' martensite are related to the features of the superelastic plateau in the stress-strain curve. Particular attention was given to study the texture of the residual austenite at the end of the superelastic plateau. On a single 2D diffraction image, lateral expansion and transverse contraction of several lattice plane reflections is recorded simultaneously. The mechanical response of NiTi polycrystalline materials and the evolution of martensite texture depend on the orientation of the loading axes relative to directions defined by the original austenite texture. This anisotropy was demonstrated in tensile experiments along RD and TD respectively. A comparison between the experimental and recalculated distribution densities for the polycrystalline NiTi shows a reasonable agreement.

• Reihe: Maschinenbau
• ISBN: 9783899662788
• Sprache: Englisch
• Erscheinungsdatum: 01.09.2007
• Genre: Naturwissenschaften allgemein
• Verlag: Bochumer Universitätsverlag Westdeutscher Universitätsverlag